This wonderful news was posted on the ASUS UK Facebook.
However neither the OTA or exact date were given, unless the word A.S.A.P to indicate the update is coming so near -- right after the Tranformer Prime.
Unfortunately the UK ICS update announcement didn't not mention anything about the US update. But people can expect the update for their tablet not too far after that.
Update: Here is the latest news on ICS update for Transformer TF101 is that ASUS is currently waiting Google's approval before pushing ICS out to TF101, you can read the news from ASUS'S FB page here. Or simply see the following screenshot:
Update: Asus Tranformer Prime gets Android ICS via OTA.
Update 2: Transformer TF101 Will Receive ICS Update In Early Februray.