My wife's iPhone 4 home button began failing right after the warranty expired of course. Apple was going to replace the iPhone for ~$150. Not a bad deal but I didn't have the extra $ around so I opted to fix it my self. I have lots of experience with repairing items, but none this small.
With the fantastic aid of iFixit's repair guides, and a little patients, I was able to repair the iPhone without any major issues. I did find a small rubber piece on the table just before I went to put the logic board back in and had no clue where it went. Once again, iFixit has a note detailing what the piece was and where it went. EXCELLENT!
I used a pair of latex gloves during the repair to avoid getting skin oil on the antenna components. Looks like this worked great as I have no signal issues at all.