I've been mining at ypool.net for almost 24 hours now. I have a confirmed balance just below the 2 XPM min. payout already.
Check there community forum for the jhminer x64 beta miner.
http://community.ypool.net/index.php?page=Thread&threadID=5
There is also a script (.bat) to restart the miner every x mins (30-60 recommended) as it is occasionally freezing on some PC's
They are actively working on a new miner to improve on traffic compression by over 80% and massively reduce the currently high level of rejects on shares. They are also working on a GPU miner apparently!
All good thus far. The pool has 3400 confirmations however, whilst they build up some pool liquidity.
I'll keep you posted.