I'm perfectly ok with the Android icon, which looks different from just about everything else and is easy to remember once learned. The Apple icon looks too generic, and there are already way too many icons that look document-ish. The Windows icon looks too much like Ubuntu to me, and it additionally isn't intuitive that a circular icon means sharing. The Dropbox & Google Apps icons are great, but are also large and wouldn't necessarily be easy to distill down into a square, single color representation.

By far my biggest pet peeve re:action icons these days are the Android copy/paste icons. Here's a screenshot I found: http://i.stack.imgur.com/87bDm.png (pardon the annotations -- I found it in a Stackexchange thread).

I challenge anyone to tell me what each one does (without testing first).