According to reports, the soak testers for the Jelly Bean update to the Motorola XOOM WiFi edition are receiving it now and are busy playing and testing. The version is Android 4.1.1, JRO03H, and there are some methods currently floating around that could potentially allow you the ability to get it on your device too. Unfortunately, most of the reports indicate that attempts to do so were not successful, so we aren't going to post it here. In the long run, this shouldn't be too big of an issue, since normally the full OTA update comes pretty quickly after the soak test. It shouldn't be long now.
Source: XoomForums via AdndroidPolice