Er, no she wasn't. The first time she fought alongside them as far as I know was during Secret Wars #1, and that didn't mean she was an Avenger, since like, everyone was there.
Anyway, Thor will get his hammer back, obviously. That was obvious from day one, Jason Aaron has already shown the future in his run, we've seen King Thor with Mjolnir, so he obviously bcomes worthy again. It's just a matter of when.