Pretty much everyone else has answered the question, but I just wanted to add how well Macs do for a traveler. With my old iBook I traveled all through Afghanistan for nine months without trouble. If there is power, your Mac will work! The iBook was also used in Germany, Uzbekistan, Serbia, and Bulgaria with no problems.
My PowerBook just spend about 11 months in Iraq in various cities with no troubles as well. It has been from Korea, Germany, Ireland, Kuwait, and Qatar. Just be sure to buy the travel adapter kits the other posters brought up!
I was able to connect to just about any network while at these different places. The only problem I had was at the international airport in Korea with the WIFI connection. I think this was just from the version of Safari I was using and not OS X. It is always good to have a backup browser just in case (I have IE and firefox in addition to Safari just to be safe).
PowerBook G4 12 1.33GHz and iBook G3 12 600MHz Mac OS X (10.4.6)