I’ve been trying to track down what’s been causing problems with uploads to the new version of gallery (gallery2). It will freak out and abort uploads when it reaches certain pictures. I thought it was weird that it would consistently not be able to upload particular pictures, and do fine with all the rest. At first I thought it was an issue with the new version of gallery and my iPhotoToGallery plugin that I use to upload, but today I tried to upload some of the errant pictures through the web interface, and it still freaked out.
What I realized was that the pictures that are giving gallery2 problems are those that have been rotated locally on my new computer. The new mac has a more current version of the iLife suite, and it seems that something strange is happening when I rotate pictures. Either the jpeg manipulation libraries on gallery2 have a bug in them, or the new version of iPhoto is doing something nonstandard with the jpeg files. I still need to investigate it further, but at least now I know where to look at the problem.