It's rare that I disagree with Nick Carr but I think he and a few others are making up a controversy that doesn't exist. Nick wrote up the web services schism.
The thesis that he and a few others are using is roughly that SOA = corporate dev/bus types and Web 2.0 = hacker barbarians. Now this is just plain fooey. What's really happened is that they are all using SOA. There's no real definition of SOA, but really it's just about building successful distributed apps. Of which the Web 2.0 folks are defintiely doing that! The quote SOA quote folks just like to build database apps and are marketing it like crazy.
It's not "SOA vs Web 2.0", the question really ought to be "why aren't more corporate environments using web 2.0 technologies". To which the obvious answer is "It's the apps silly".
The reason why a lot of the corporate apps aren't very google mappy or flickr apiy or bloggy or wikiey is frankly the corps have *LOTS* of stuff in enterprise apps and databases. Some trading exchange company that's doing data enrichment of trades with risk information etc. just doesn't need maps/flickr/blog/wiki.
Now why isn't the trading data enrichment app built using Ajax, etc.? Well, some of them are, but mostly it's just way smarter to move the processing closer to the data, ie the server, ie the "corporate" environment. When you can offer 2x perf over a competitor by doing the data integration on your server and enforce SLAs on your partners, it's a nobrainer.
SOA vs Web 2.0 debate is smoke no fire.