Asus has now started rolling out the update to Android 4.1 Jelly Bean for its Transformer Pad Infinity and TF300T tablets. It has been reported that few days ago an over-the-air update first appeared and surprised users by actually bumping up the version on their tablets to Jelly Bean.
Users can  go  and check if they have an update pending, but don’t worry if it still hasn’t arrived for them because there are  chances that it’d come in the next few days. In last month Asus promised the update to its tablet lineup and now it’s available. As declared by Asus "We are pleased to announce that we will be updating many of our tablet products to Android 4.1, Jelly Bean. The ASUS Transformer Pad, ASUS Transformer Pad Prime and ASUS Transformer Pad Infinity are all scheduled to receive an update to Jelly Bean in the coming months".
Android 4.1 Jelly Bean brings vast improvements in the smoothness of Android, and also introduces Google Now, a card-based system of automatic notifications along with better Google Voice Search, an intelligent voice assistant that is faster and more accurate than Apple’s Siri.

Source : Phonearena