support and accountability
yes, I know as well as anyone that accountability in software is never much more than theoretical, but that little bit of possibility that you could take legal action against the manufacturer in the case their product causes your factory to blow up is a big thing for corporate boardrooms who think in such things (and have to).

Support is another thing.
If I buy Novell Extend server (formerly Silverstream) it comes complete with training, thick printed manuals, on-site experts to help you implement it and if necessary keep it running.
With open source all you typically have is a mailing list where someone may or may not respond before the house burns down.
Need some custom work done? If you got an IBM (or insert your company here) contract they'll do it for you. With open source you have to beg and plead and hope someone will think it an interesting mental challenge.
Of course there's some companies selling support around open source products, and they're doing a decent business off of it. But having the original manufacturer around to help you out is a good feeling for corporate decision makers (and those guys often really ARE good in making the product sing).

Then there's the pirate and amateur image the entire open source community still hasn't shed and seems unwilling to shed.
The constant attacks on corporate entities, refusal to accept that companies CAN produce good software and have good ideas (thus reinventing the wheel and making it oblong just to be different), and other overly zealous idiocies are not helping to present a mature and professional image of the products to the corporate decision maker.

If I go to a major financial institution as a consultant (or whatever function), I go in suit and tie.
If the group I'll be working with is less formal, the suit and tie disappear into a closet and I take the back entrance into the building the next time.
Many open source guys would arrive in jeans and a Linux T-shirt with pizza stains...
They don't speak the talk, they don't walk the walk. Whether it is because they don't KNOW how to behave in a corporate environment or elect to not behave I don't care, fact is that someone at board level in a multinational (which is where, like it or not, IT decisions are being made that affect the entire enterprise, sometimes down to which editor the programmers can use) is far more likely to buy the services I offer (who appear in HIS type of clothing and speak HIS language) than the services offered by that scruffy guy in his faded corduroys who reminds him more of a taller version of his least favourite grandson.

support and accountability
addendum:

I've worked for several multinationals in a consultancy role, writing software.

The examples I give are taken from real life, I've indeed seen Linux people arriving in the headquarters of a large bank wearing faded jeans and torn T-shirts to board meetings...

I've also implemented open source products there myself.
But the arguments I used were not religious.
They were based on cost-benefit analysis.

We need something that does X. Writing it ourselves will cost 3 months fulltime.
Taking that open source project aboard which is 90% what we want and helping bringing it to fruition will take 3 weeks parttime.
That's money talking, that's what decision makers in enterprises understand.

Other open source products are just sneaked in by the developers. Mainly these are libraries like Xerces where developers will just use them without asking, but this requires an environment in which developers have some degree of freedom (which can be rare depending on the company).

support and accountability
You certainly have colorful opinions on the subject open source, but I really have to question the factual basis of your stereotypes.

Firstly you name two companies to emphasis the businesslike attitude of proprietary software development in order to contrast it with the open source hippy mentality. And yet, out of the vast range of IT corporations, you manage to choose Novell and IBM, the two companies from the proprietary era who have most strongly nailed their colors to the open source mast.

If you go to novell.com at this very moment there are four mentions of Linux and one of 'open source' right on the front page. Not to mention a penguin (signifying Linux, of course), a green chameleon (Suse), two monkeys (Ximian and Mono) and footprint logo (Gnome).

Something tells me that Novell salesmen don't turn up to meet clients in faded corduroys and that Novell will be more than happy to take money for consulting and support if that's what their customers want.

support and accountability
Do not mistake individuals for some amorphous "community". There are no membership cards, no rites of passage, and no standards. There is as much a community in open source as there is for people who drive cars (meaning, not much, and anything you do find is highly fragmented, as you yourself attest).

If you do not like the way people show up for work, take them aside and explain it to them. If they persist, find someone else.

There are plenty of people who work with open source who know how to dress and act properly. Do not blame everyone connected with open source for the dumb mistakes of a few, or let a vocal minority dominate the image.

Stereotypes
Social stereotypes linger for years and even decades, so it is perhaps human nature to create stereotypes for software development communities and organizations. The problem is that the pace of technology is fast, and the stereotypes just do not apply.

The initial link http://osdir.com/PNphpBB2-viewtopic-t22-.phtml mentions a German software developer asserting that German companies are eager to contribute to open source projects but are hindered by their employees. What is view based on? I have worked for a large (30,000 employees) German software company for the last five years and cannot confirm that view. Only sporadic contributions to open source communities has been made, and these are of no strategic importance to the company. This is just a business strategy, so it should not in itself be the cause for polemics. The case for 'German companies' is just a stereotype, since the large companies are multinationals and they will not have much nationalistic behavior.

Another commentator in this weblog describes the failings of open source developers, with their (sic) jeans and a Linux T-shirt with pizza stains. This view is so out of synch with reality. It suffices to say that companies such as IBM, Sun and Apple have embraced open source projects. There are even companies specializing in providing services for open source systems (Red Hat and JBoss come to mind). Whether they allow t-shirts in meeting rooms is unimportant. The dress code where I work is relaxed but our products are proprietary. At best, the comment can be seen as the common argument that financial institutions do not bank on open source systems. And that is perhaps rapidly becoming an outdated stereotype...