This one isn't going to go away for a long time. Re-writing applications to run in 64-bit native mode is expensive for any developer/company. And really, what applications absolutely positively NEED the extra memory? I can't name a single client-side application that requires 64-bit operations - unless you're running a 3D CAD program. Databases, etc. are run server-side, and they're the other major memory eaters.
I've also personally had a lot of problems with the so-called 64-bit native apps that are out there. Even mainstream programs like MS Office and Adobe Acrobat in 64-bit version have given us problems that magically disappeared as soon as we went back to 32-bit versions.
I still see this one as being a low priority, primarily just for the reason that the common desktop really doesn't NEED 64-bit support.
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