I'm a new iphone 3GS user and abit confused with the issue of upgrading to OS 3.1 and losing the carrier unlock.

Quoting the dev team:

If you update to Apple’s new software using the normal iTunes process, you will lose your ultrasn0w unlock. In fact you may lose it permanently, because for most people the baseband firmware cannot be reverted to a previous version (unlike the main application CPU firmware).

My iphone is from maxis which is officially unlocked. So I think 'losing the unlock permanently' as quoted by the dev team does not affect my iphone?

It only affects those iphone that are initially carrier locked, and then unlocked by ultrasnow unlock.

Am I right?