I've updated to Lion. I decrypted the drive first. Worked. However, I didn't de-install PGP and now it's bitten me big time.
Just upgraded to 10.7.2 and it BRICKED my machine. Two symptoms - listed here in an attempt to help other poor souls who find themselves in the same position...
The update runs and the machine refuses to boot. Verbose mode (cmd+V when booting) shows error 0xe00002c9 and the disc turns off.
Mounting the disc using the disc utilities (cmd+R when booting) allows me to mount it (it's encrypted using Filevault2) and run a disk check which yields the message "Unable to bootstrap transaction group xxxx" but it continues through and says it completed OK.
The fix is to re-install Lion over the existing system. This means that the system boots.
However, upgrading to 10.7.2 BRICKED THE MACHINE AGAIN (e.g. fails to boot, crashes at statup) meaning I've lost a total of three days without my computer. That costs me a lot of money.
In my opinion, Symantec are completely to blame and have failed in their duty of care to their customers. No warnings, updates, nothing. Oh, they're damn quick to ask for money. I will never deal with Symantec for as long as I live and will make it my business to stop other people (victims?) using them.