Keeping true to its reputation for timely updates, ASUS pushed out an official Jelly Bean OTA update to lucky Transformer Pad TF300 owners in North America last Saturday after a quick tease. Now, under a week later, it looks like ASUS has provided the full firmware for download directly from its support site.
The download, which those who didn't receive the OTA (due to an unlocked bootloader or otherwise) can use to get to ASUS' clean Jelly Bean experience, weighs a hefty 438MB and is meant only for users of the US version of the TF300. It's worth noting that using ASUS' downloadable firmware to upgrade to Jelly Bean will break root and overwrite any custom recovery you may be running. If you'd rather not take that route, you need only wait for intrepid developers to cook up a rooted ROM based on the update.
Download: ASUS Support