Followup. I found a different Amazon S3 uploader plugin that seems to be working under v1.0.0. If interested see here
0.11.x plugin statuses
I'm looking to upgrade from 0.10.x to 0.11.x. Is there a script or something which will tell me what plugins are not designed for 0.11.x?
Most likely there weren't any major breaking changes for plugins between those two versions. You should be okay to upgrade, although I'd back up your database just to be safe.