There is already an Android 4.1.1 Jelly Bean ROM available for the Galaxy Tab 10.1. I am loving the continued development for a tablet that is over a year old now. The ROM is in an Alpha version and is classified as experimental. Many things do not work like the camera, audio, and hardware accelerated video.
This ROM is available for the Wi-Fi only Galaxy Tab 10.1 (GT-P7510) and the Wi-Fi + 3G Galaxy Tab 10.1 (GT-P7500), but Wi-Fi only works on the Wi-Fi only model. I am not sure if 3G works on the Wi-Fi + 3G model.
I am flashing it now and will post a video soon. You can find flashing directions here.