OG Transformer already has a rooted ICS ROM
The Android 4.0 Ice Cream Sandwich update for the Asus Eee Pad Transformer just started rolling out yesterday, but the mod community doesn't need a lot of time these days, which means that there is already a rooted stock ICS ROM for the tablet. Yesterday, Asus began the rollout for Taiwan versions of the Transformer, and today started the rollout for the worldwide and US versions.
So, essentially the rollout began, and MrNago at xda got his work done lickety split. The amazing thing is that this ROM can be flashed very easily, just like any other custom ROM. Usually, OTA updates like this don't allow that, but MrNago has got this working all around.
Just one warning: if you have a model TF101G, do not install this as there are a lot of issues with random reboots and bugs. The only known bug so far with the ROM on other TF101 versions is that USB to PC may not work, so you may have issues with ADB.
source: XDA developers