The maxsendbuffer bug (0.3.20.1 clients not being able to download the block chain from other 0.3.20.1 clients) was only going to get worse as people upgraded, so I cherry-picked the bug fix and created a minor release yesterday.
The Amazon Machine Images I used to do the builds are available:
ami-38a05251 Bitcoin-v0.3.20.2 Mingw (Windows; Administrator password 'bitcoin development') ami-30a05259 Bitcoin_0.3.20.2 Linux32 ami-8abc4ee3 Bitcoin_0.3.20.2 Linux64
(mac build will be done soon)
If you have already downloaded version 0.3.20.1, please either add this to your bitcoin.conf file:
maxsendbuffer=10000 maxreceivebuffer=10000
... or download the new version.