A preliminary combined diff is now available.
http://davids.webmaster.com/~davids/bitcoin-3diff.txtFeatures:
1) RPC enhancements to support JSON parsing in a thread, concurrent handling of multiple RPC connections, and working HTTP keepalives.
2) Native long-polling support. New option "-pollpidfile=/path/to/pidfile". Pass in the path to your pool manager's PID file. (By default with pushpoold, it's "/var/run/pushpoold.pid".) This is faster than blkmond and eliminates the need to run it. (In fact, DO NOT use blkmond with this option as you'll wind up telling your miners to abort valid runs.)
3) More aggressive connection management. Outbound connections are made in their own thread and the client tries more aggressively to get more of them. This should mean both that you find out about new blocks faster and you get your own blocks out faster. This is most noticeable when you just restart bitcoind, as it tries very aggressively on startup to re-establish connectivity. But the benefits should accrue all the time -- you'll be working on a longer chain faster and others will be working on extending your blocks faster.
The changes to 'net.cpp' should not be used on machines with limited net connectivity as more connections will mean more traffic. Currently, these changes are not very tunable. (I plan to add a '-hub' option that will enable these features to make you more of a 'hub' of the BitCoin network.)
Test reports, suggestions, and donations are all welcome.