I'm the first to bash Microsoft when I feel they deserve it (see my recent posts on 5 reasons to get Vista), but when incompetents do the same with no technical ground I'd rather side with them. A nonsense study by Evans Data (see Tim Anderson report here) places developers writing applications for vista at a mere 8%, and c|net makes a fuss of it (see Steve Trefethen comment -- I agree with him, better not link similar articles).
I fully agree with Tim: as a huge portion of the Vista API (both in native Win32 form and in the .NET form) is available on both platform, what does it mean to target Vista or XP? I doubt that "XP developers" don't check their programs on Vista these days. And what about Delphi 2007 developers? Simply by recompiling existing Delphi applications with the latest version of the IDE an application becomes Vista enabled. For example, all MessageDlg call are redirected to the new Vista-specific TaskDialog API. Similarly, a WinForms developer is equqally targeting XP and Vista.
Speaking of Microsoft (in not to positive terms) you might want to look at the discussions around the future of LINQ and also this post about the terrible performance of the stock over the last 8 years. I know I'm digressing but I'm between trips (Germany, Sicily, seaside) and doubt I'll have time to blog more about these issues.
PS. I probably won't approve posts until Monday, as I'll be a few days off line.