A bit less than two weeks ago, the TF300 became the first non-Nexus ASUS tablet to receive an update to Jelly Bean, starting with the U.S. Several days later, ASUS posted the full Jelly Bean ROM v10.4.2.9, though only for U.S. variants, and almost immediately started the OTA rollout in Europe.
If you have one of these TF300s with a WW (worldwide) or TW (Taiwan) SKU and haven't gotten the OTA yet (or messed something up and want to restore), the full ROMs are now downloadable from the TF300 support page (select Download -> Android):
Since ASUS' site often times out, I'll save you a few minutes of frustration and provide all 3 direct links:
- ASUS TF300T Jelly Bean firmware v10.4.2.9 TW SKU (439.46MB)
- ASUS TF300T Jelly Bean firmware v10.4.2.9 WW SKU (428.65MB)
- ASUS TF300T Jelly Bean firmware v10.4.2.9 US SKU (438.56MB)
To check the region variant of the software on your TF300T, go to Settings > About tablet and look at Build number.