Here's my success story:
Between each attempt I did a full restore from a clean backup. My iPad was purchased with 3.2.2 already on it 3 weeks ago. It has never been jailbroken before. All attempts with BETA 4 unless otherwise noted.
iPad 3.2.2, tried limera1n on Vista x64, UAC off, fully updated iTunes.
Attempt 1 - Failure, tried with BETA 2, didn't count timings on button presses
Attempt 2 - Failure, didn't count timings on button presses
Attempt 3 - Failure, after a clean reboot
Attempt 4 - Failure, watched 2 videos and counted off button presses with 10 seconds each combination (10 for home+power, 10 for home)
Attempt 5 - Failure, tried with iTuneshelper.exe closed, counted off button presses.
Attempt 6 - Failure, tried with a different USB port, same computer, counted off button presses. iTuneshelper.exe was running again.
Luckily, I had just reformatted my girl's laptop with WinXP 32bit. Clean install of iTunes 10 most recent version.
Attempt 7 - Success! Counted off button presses, limera1n drop appeared and I had white icons for it. I rebooted the iPad as advised on limera1n's webpage (held power button and slide red slider) and the white icon remained. Installed Cydia anyway, rebooted again, and white icon was fixed.
My advice to those still having problems:
1. Count off button presses, 10 seconds for home+power, 10 seconds for home alone.
2. Try a 32bit operating system if you are still not getting it, preferably with a clean install of iTunes.
I really think the problem is that geohot didn't test this very well with 64 bit OS's, combined with user error on the timings of the button presses, as well as very minor differences in iTunes settings or versionings. Don't give up, as after attempt 4 I was pretty certain that my iPad was unjailbreakable but I kept at it and succeeded.
I was pretty scientific with the button count offs, so I don't think that it was ever going to work on my Vista 64 installation. My theory is that it was the 32bit OS that let this work, but it could be the clean iTunes install on it as well.