I agree with what has already been said. If you normally make long calls then any phone also is susceptible to heat due to the prolonged heavy discharging of the battery during a call. Not to mentioned as what Benny said about radiation concerns.

If you are so concerned about heat then think about this - many years ago it was considered trendy to hang your phone around your neck. IMHO it was a bigger concern coz not a lot of people bother to think about radiation concerns placing the phone so close to your heart for an extended period of time.

This solution can be solved by considering the use of a Bluetooth headset. Solution already exist and if you decide to hold back then it a personal choice.

Just to reaffirm benny888's note on Skype.
I was able to download it with using Market Enabler and/or tweaking the phone/system to make it look that I am using a foreign SIM.

I read all the posts today and this question pops up like 2-3 times. Yes ... can be very upsetting if such simple questions are asked repeatedly and every one just come in here and ask thinking we are Android Google.