Matt, whilst the SAR values are a good measure of power, the trouble with 3G, being around the 2.2GHz mark is that it's a greater frequency.
The signal drops off in power over distance a lot quicker than 2.5G, but it should be the same power.
HOWEVER, bluetooth is in the 2.4GHz range, which is even more damaging at the same range.
I personally think you're more likely to run into a bus whilst using the phone rather than having your head fried :-)
Rgds,
Paul