The answer is Definately!
I live in New Zealand and i'm running a 1.1.2 iPhone using a TurboSIM. Updating is not hard, all you need to do is:
1.) On an activated 1.1.1 iPhone, go to Installer and install Oktoprep (found in tweaks 1.1.1?)
2.) Update! to 1.1.2 through iTunes
3.) Download
1.1.2-jailbreak. If you are on a Mac, click Jailbreak.jar. If you are on Windows, click jailbreak.bat. (Ps. I use windows)
4.) This will activate your iPhone aswell. To fix the SMS and Phone crashing issue, install iWorld from Tweaks (1.1.2) in Installer.
This would have to be one of the easiest updates yet!