Opera 9. It just worked for me as well. It didn't work the dozen times before that I clicked on it all morning, and I haven't so much as quit and restart the browser, but I'll go ahead and say it still has to be user error on my part somehow
Thanks for confirming at least that it was working for others. Sorry about the false alarm.
Opera 9.01 came out yesterday. They don't mention anything specifically about RSS hangs in the release notes, but there are some unspecified "stability improvements" in there along with a healthy list of listed fixes.