Heh - I had created #bitcoin-btcmine and had been idling in there...
One question - for last block solved, (118405) I submitted 18104 shares against the 166,119 shares total or 10.899%. My bounty was just 4.184 BTC.
I would have suspected 50 * .98 (2% commission) = 49 * 10.899% = 5.34 BTC. Why such a large discrepancy?
I will take a guess that the discrepancy arises because BTCMine uses a score-based method and not a proportional-share method. So your calculation should be based on your "score / total round score," rather than "your shares / total shares."