Goto ASUS.com, goto SUPPORT>DOWNLOADS>Put in Transformer Prime. Select Android OS and then FIRMWARE. Download this: Eee Pad Transformer Prime TF201 Firmware: V18.104.22.168 Only for US SKU (Android 4.0.3)
It will be a ~300mb zip file. Once its downloaded, extract it, its a zip inside of a zip. Once you get the new zip, place it on /sdcard/ and power off your device.
Once I turned mine BACK on, I went to System, About Tablet and checked for a FW upgrade. It saw the file I put on and allowed me to reinstall 4.0.3 ICS, afterwhich I was able to get tonights OTA.
I know this isnt anything special, but trying to get info out of the current thread is tough.
If your device doesn't see an update after you put the zip on your tab, try powering off, holding POWER and VOLUME DOWN and then pressing VOLUME UP once you get to the screen with tiny text. It will attempt to update that way but fail, and youll get a message once you get back to your homescreen that a update failed and you can attempt it again that way.