Since bigrushdog et al haven't yet posted updated kernels for Honeycomb 3.1 and my overclocking itch needed scratching, I thought I'd share my kernel for Xooms running 3.1 for any other impatient souls. This is forked from AOSP, but with some features like micro SD support borrowed from Tiamat

The kernel is configured differently, but everything you'd expect from Tiamat should be present (well, except for tun.ko) including the 1.504GHz clock speed.
To install, place the appropriate zip file on your micro SD card and use ClockworkMod Recovery's install zip from sdcard option. You can also extract boot.img from the zip file and flash using fastboot from your PC.
WiFi-only
WiFi+3G
I don't use github at present, so the source code lives on my PC. If you want it for any reason, just let me know. Many kudos to bigrushdog, coolbho3k and Koush.
Some benchmark numbers (take with sufficient salt)
Linpack:
63.995 MFLOPS
Nenamark1:
52.1 fps
Quadrant Standard:
4034