I've only mentioned one new feature so far - multiple group addition - and I'm going to keep the others to myself for now, but I promise you'll really like them. Not every feature ever requested is going to be in v3, that's for sure, but I get a ton of feedback, so I really think I know what most people want out of the next version.
It was slightly unexpected that Apple would announce a Plugin SDK with iPhoto 7, but certainly a welcome surprise. FlickrExport 3 will adopt the SDK fully, but it's too much of a rework to do it for FlickrExport 2 right now. There's not a lot that it adds to the experience, and in one respect it's inferior to FlickrExport's current arrangement, but it has the massive advantage of being documented and supported going forward. If I have to take one step back to take ten forward, I'll do so. The aspect I'm referring to is the export progress dialog. FlickrExport has two progress bars - one for the overall progress and one for the per-photo upload progress. The iPhoto SDK only provides a text string and one progress bar to give feedback to the user, so the overall progress feedback is textual and the progress bar is used for the upload progress. That's exactly how Aperture does it, and it's a perfectly OK way to work.