I've got a 2006 SR5 (193K miles), and I had the dreaded "won't shift out of park" episode the other day, and after searching the forums, I looked at all of the fuses in the area to the left of the steering wheel and none were blown (I was thinking it might be a brake lights issue, but I had the wife press the pedal and they both worked fine).

Long story short, it happened a few times, and I was able to get it shifted by using the shift interlock button to release it manually. After I checked all the fuses and replaced them (as none were blown), I haven't had it happen again. I'm not worried if it does as I carry a small Gerber-type tool in my vehicle just in case, but I'm just curious if anyone has other ideas on what may have caused it. Seems like it could be a variety of different things, but I guess I thought for sure I'd find a blown fuse of some sort.

As an aside, I will say that I had some work done on the rear bumper lately (picked it up on Friday from that work and this happened Saturday morning), and seeing as I have a tow package installed, is it unreasonable to think that perhaps when they were doing the work to the rear bumper, they messed with the wiring harness for trailer light hookup? I've hauled trailers and things before and never had any issue that I was aware of...