The news was announced during the NVidia CEO Jen-Hsun Huang's keynote presentation during the CES 2012.
The update makes the Asus Transformer Prime the first Android ICS tablet available in the market. The Transformer Prime which is the successor to the Asus Eee Pad Transformer features a 10 inch display, 8MP camera, up to 64GB of internal storage, an optional keyboard dock and is powered by a quad core NVidia CPU.
If you own a Transformer Prime and have not received the update notification you can check if it is available manually under settings or wait for until you receive a notification from Asus.