The T-Mobile G2X (LG P999) and its international version, the LG Optimus 2X (LG P990), are receiving CyanogenMod 9 builds so if you own one of the aforementioned devices and you were waiting for Ice Cream Sandwich, here it comes.
However, as Ricardo Cerqueira points it out, these builds are not supported "and updates may or may not happen in the future". Before you rush to the source link to download and apply the custom ROMs you should know that there are a couple of things that are not working. There is no acceleration for media neither for video decoding nor encoding and applications that employ specific Android 4.0 Ice Cream Sandwich graphics implementations will have some issues. However, if you still want to check it out, follow the source link below (and, as usual, note that tampering with your device could render it unusable).