I've managed to compile matplotlib under Windows 7, but it was a bit of a fight and I felt like a kludged one too many things. I've not been able to find a guide for building matplotlib on Windows, except for a smattering of newsgroup posts a long time ago (http://sourceforge.net/mailarchive/message.php?msg_id=27961105)

Really this info needs to be on the website before it becomes a lost art; apparently someone is doing it (Christophe probably?) because the Windows binary releases continue to show up ;)