I flashed the ICS beta yesterday. It was quite a process, and it took me a while (6 hours or so, including the wait for downloads) to get it right. The guide in the thread on xda didn't work for me, but I found alot of useful info on
the thread (pages 347-351).
Here's a quick guide for those wanting to try, perhaps it will save you some time.
Basically what I did (coming from miui):
Flash stock jvt with Odin3 v1.30
Flash latest speedmod kernel
WIPE
Flash CM7.1
Phone enters bootloop
Flash CM7.1 (Again)
flash cm radio jvt
WIPE
flash ICS kernel
Flash ICS rom (beta1)
reboot (Phone will most probably not boot correctly)
Flash ICS rom (again)
Flash ICS kernel(again)
And now its working...very well.
Things that I did wrong:
First I tried flashing direct from MIUI (JVK base), the rom flashed but would not boot.
Then I flashed CM7.1, and then ICS (once again I the rom instalation would execute, but the rom would not boot)
Then I reverted to stock JVT with CF Root kernel and tried ICS direct from JVT, but kept getting errors in CWM.
Then I tried Stock JVT with Speedmod kernel and got the same error.
Then I followed the process laid out above.
PM me if you would like to try and want a link to one of the files mentioned above...