There's an update waiting for you in the LG Mobile Support tool if you have a T-Mobile G2X, but relax -- it's not Ice Cream Sandwich. V21Y brings the G2X to Android version 2.3.4, swaps out the baseband for a newer version, and adds Google+ to the ROM. Early reports say that battery life has been improved, but that great LG camera app is still nowhere to be found.
Other than that, it looks to be a small version bump from 2.3.3 to 2.3.4, and was "released" with no fanfare. We still don't know when (or if) the G2X will ever see an official Ice Cream Sandwich update, and that makes us sad. Anyone who has one will tell you it's an amazing piece of hardware, simply held back by buggy radios and software.
If you're feeling brave, and have a stock G2X (or can take the time to roll back to stock), plug in and check for updates and give it a try.