Just look at some of the celebrity CEO bloggers. Jonathan Schwartz at Sun is a great example. He wields it as a powerful marketing tool, getting exposure for his ideas without spending money on advertising. If you have top execs who are willing to speak for the company, this is huge.
But even mid-level people can have a big impact if they are given the freedom to speak their minds (especially if they have useful insights.) Look at the various google blogs -- Matt Cutts on search engine optimization, for example. He's the man, or the voice of the man, on this important topic. It allows google to be in conversation with its advertisers and their opponents.
Another thing to remind your management of is a bit of history. Just remind them when all those arguments were used against the personal computer. IT hated and feared PCs. And sure enough, there were gaffes, when people made bad decisions based on flawed spreadsheet formulas. (There was even a suit against Lotus over a couple of those.) But in the end, the value was too great to ignore.
While blogs et al are now only at leading edge companies, eventually they will be everywhere. So it's really a matter of now or later, not whether.
As to other aspects of your post -- I'm very interested in thinking about applications of Web 2.0 to manufacturing. I'd love it if you'd post a URL for your company, so I can look at the apps you have that let customers interact with your products. You can also send me an email -- tim at oreilly.com -- if you don't want to publish that here.