15 BTC with units shipping now is clearly profitable:
http://mining.thegenesisblock.com/a/44fc645248 (55% month-over-month difficulty increase), and even a pessimistic
100% month-over-month increase is profitable. Also,
15 BTC for 105 Ghash/sec beats the price per Ghash/sec of any competitor shipping now or in October!
That's only true if you go back in time and start mining Sept. 1. If you start on Oct. 1 they are only profitable by 0.05 BTC with 55% diff increase and 100% increase is just bad.
Edit: I miscalculated the 55%, they are profitable if it is only 55%. But I don't believe 55% will be what we see.