Some random comments:
When Apple first announced Xserve, there were some interesting posts on CF-Talk, one of the lists I really like -- it's participants are some of the major players in CF development and hosting.
The nay-sayers said that the hardware lacked SCSI disks, and that Apple had no history as a general-purpose server vendor, but other than that they were impressed with the specs -- I got the feeling that they were impressed, but not convinced -- a wait and see attitude,
The yea-sayers were really impressed with the specs, the ease-of-use, the (implied) capabilities and the very low cost of ownership. (OS X Server software doesn't charge per CPU on the server or number of clients attached -- so the server software cost is negligible).
Something that most people don't realize is that OS X includes a complete Java runtime and development environment, as a standard feature -- AFAIK, nobody but Sun does that.
The Sybase and Oracle announcements, while very low-key, got some attention in the server marketplace -- If these "heavyweights" think that OS X is a viable platform, shouldn't we too? Most Noticible was the IBM survey to see if there was enough interest to release DB/2 on Mac OS X.
The recent announcement that Apple will package MySQL with OS X Server software is also significant -- Apple (and others) can now package complete dynamic web applications for the OS X platform, in several languages.
AFAIK, there is currently no officially-blessed J2ee-compliant application server for OS X -- so this is a weakness.
I read somewhere, that since the XServe announcement that Apple is the fastest growing (percentage increase) vendor of servers -- of course they are coming from a very small base, but still---
I spoke on the phone, for about an hour, with Darryl Salas of Sybase. He said that they had made a major investment and effort to make Sybase_ASE on OS X, easy to setup and administer. He said that they had met most of there objectives and felt that the Sybase OS X combination was better in these capabilities than any other major database. This is significant -- it could drastically reduce one of the major costs of owning a database
Sybase includes a feature that uses Rendezvous to recognize and automatically connect (with proper authorization) to any Sybase database on the network (wired or wireless).
I can envision going into a client's board room for a presentation, with my TiBook. I would automatically connect to the clients DB, do a little Ad Hoc programming in CFMX (The Phone list) with the client's live data -- and no wires! It would be so cool, and so easy, that I'd have to work to get anyone to believe it.
For me, the major missing piece is a supported CFMX product on Mac OS X. Macromedia people are quite aware of what Apple is doing and the acceptance of its OS X products -- I hope they can (and will) justify releasing CFMX for Mac OS X.
So, is there a potential for Macs as servers -- in my opinion, there certainly is. What the Mac has done for the 'Nix desktop (ease-of-use) it can do for the server -- and it is sorely needed!
If Apple can match the technological, reliability, support capabilities of other vendors, and offer ease-of-use and cost-of-ownership advantages -- their potential in the server market is unlimited.
I think that are very close to achieving the above -- next they need to get the word out and sell their superior solution.