burnside, add the ability to reduce difficulty for a certain worker so that shares are found easier.
why
A number of pools implement variable-difficulty shares so that any given worker is submitting at a roughly constant rate whether it's a CPU-mining Raspberry Pi or an overclocked 6-GPU monster. It helps the pool by preventing it from being share-spammed into oblivion by large rigs, and helps the miner by giving relatively stable error bounds on share submission.
Vardiff is great but the pool software has to support it. (I doubt pushpool does) The only version of Stratum that works with Litecoin is the vipaerus modified one, and that one doesn't support vardiff. So he'd have a fair bit of programming to do to implement vardiff on his pool.