Following a few problem reports from Aperture 2.01 users, I've now confirmed for myself that version 0.5 of Aperture2Gmail will crash when used with Aperture 2.01.
Emails are sent successfully, but Aperture will usually crash afterwards. I've narrowed down the fix and will be posting an update that resolves the problem. It has been difficult to test against Aperture 2.01 because I only have the 2.0 trial and had to re-download the whole trial app to get the 2.01 update. Fast and free internet has sometimes been difficult to come by on our trip through Europe, but I am doing my best!
Until version 0.6 is released, Aperture2Gmail v0.5 should be avoided if you are running Aperture 2.01.