I'm seriously convinced there is a hardware fault with some phones, as this is like the 30th thread I've read that goes along the lines of:

A. "N900 GPS Suxxors!"
B. "No it doesn't, works fine for me"
C. "Yes it does Suxxors!"
A. "See? Is Suxxxors!"
B. "But it works for me, ergo A + C are idiots"

Is it not possible that some revisions of the N900 got dodgy GPS hardware fitted, which would explain the varying results people are getting (reception and A-GPS aside).