Just a couple of weeks ago the US version, followed by the European versions, of the Asus Transformer Pad TF300 received the Android 4.1/Jelly Bean update. They became the first Android tablet to get Jelly Bean after the Nexus 7. Now Asus has released the download for the update for the Worldwide (WW) and the Taiwan (TW) versions of the tablet. If you haven't seen the OTA you can check manually by going to Settings > About tablet and look at Build number. Beyond that, here is the source link below.

Source: TransformerForums via Asus Support