According to an announcement made on the official Star Trek Online website, a public, playable demo of Star Trek Online will be at this year's Penny Arcade Expo! Looks like PAX is really shaping up to be a great show!
I ended up with a lifetime subscription to Champions. So I'll be allowed in the closed beta for ST online when it becomes available. Looking forward to it, though I doubt my lifetime subscription will carry over which is disappointing.