Someone is apparently “testing” the main bitcoin network by flooding it with 0.01 BTC transactions from A->A and B->B, where A and B are two random public keys. You can watch at http://theymos.ath.cx:64150/bbe
We’ve hit the free transaction limit on each block, for many blocks now — appears to be ~219 free transactions per block. “real” transactions do not appear DoS’d at this time, presumably due to logic that prioritizes, in part, based on transaction value.