https://github.com/bitcoin/bitcoin/pull/686
Testnet difficulty calculation changes, to take effect Jan 1 2012
Allow mining of min-difficulty blocks if 20 minutes have gone by without mining a regular-difficulty block.
Normal rules apply every 2016 blocks, though, so there may be a very-slow-to-confirm block at the difficulty-adjustment blocks (once per month, assuming testnet is in it's normal "difficulty too high for number of people mining it" state).
This will almost certainly cause a testnet blockchain split after Jan 1. After pulling I'll update the Testnet Faucet, I'll ask theymos if he can update the testnet block explorer bitcoind.
I didn't implement any "shun blocks from the future" or "prefer blocks with more memory-pool transactions", I want to see how well the simplest-thing-that-might-possibly-work solution works first.