Last year, I started running the 64-bit Snow Leopard kernel so I had the need for a 64-bit compatible build of MacFUSE (since using sshfs is part of my daily routine). MacFUSE has been abandoned since 2008 so there was no 64-bit build available. I found some instructions to hack the MacFUSE source to allow it to build for a 64-bit kernel but there were some major problems with that, the main one being concurrency issues. Because of the instability of the hacked MacFUSE library, I stopped using it and had to revert to using the 32-bit kernel instead.
Then, in September of last year, Tuxera released some patches for MacFUSE that enabled a safe 64-bit build. They implemented some locks that fixed the concurrency issue of the other hack.
Early this year, MacFUSE was forked into a project called Fuse4X. Fuse4X implemented Tuxeras patches and brought the project up to date with the latest fuse sources. Fuse4X is actively being developed and works great on 32-bit and 64-bit kernels, Mac OS X 10.5 and up (Intel only). I'm running it on Lion and it's working great! Here's the link to download the latest build: Fuse4X
If you still want to use MacFUSE on 64-bit Snow Leopard or Lion, use this build: MacFUSE.pkg.zip