I am using it and it is mostly ok. apple changed the default ABI to amd64 from i386, but IIRC uname -m shows i386. last I knew, pkgsrc forces the abi to i386 for pkgsrc-compiled stuff. But there was a time it didn't. So you may have old packages built wrong.
It's not quite like that - the ABI defaults to 32 bit (there was a discussion on tech-pkg or somewhere similar), but uname -m doesn't mean that the ABI will be 32 bits. All Macs except for Xserves default to the 32 bit kernel, but of course will run 64 bit apps (that is, except for the early Core Solo and Core Duo systems).
But Greg may have something there - if the default at one time was 64 bit and you built some stuff, then updated and the default is now 32 bit, you might need to rebuild things to make everything happy.
BTW - I've had no problems with wget, but my system is explicitely set up with ABI=64. Did it fail all the time, or with just certain actions?
John