Mac Pro gets stuck in "safe mode" after Lion upgrade
Boot to single user mode (Command-S) and see what fsck shows. 


/sbin/fsck -fy
repeat the prior up to three times if needed


Assuming it boots, you can halt and then boot in verbose mode (Command-V) to restore all the console glory. 

You can also peek at /private/var/log/system.log while on single user mode to see what was happening when the clock was passing faster than the gray progress bar.