Danarc,
I've just noticed the same. It heats up little more than with 2.1. No big deal either..Maybe it's something to do with the performance increase...
new feature apple incorporated for the winter season, iphone 2.2 comes complete with a handwarmer function! We all know you cant use your iPhone with gloves, so stevie is looking out for us iPhone users who have to use the iPhone in cold weather!