If you're a software developer and you're working on software that claims some influence by GTD, read on...
I'm keen to create an agreed-upon xml standard for import & export of our GTD data. This will mean that people will be 1) able to try an app out because they can easily import and 2) not be locked into a proprietary format because they can export again. Good for developers, good for users.
I've already got some blogger support and seen some previous talk of something similar, so I know you're out there... So, if you're keen, mail me at richard (at) tudumo.com and I'll add you to the Google group. In the mail, please mention which app you're a developer of.