I was running the stable 0.7.2 bitcoin-qt client (under OS X 10.8.2) for a couple of weeks, with the block-chain completely sync'ed on an ongoing basis. No transactions in my wallet.
I upgraded to the 0.8.0b release, and it spent a few hours reindexing the entire blockchain and catching up. So far so good.
0.8.0 client continued to run normally (launch, download / sync new blocks, etc.) for several days.
Then, today, it crashes right after loading the wallet, but before it attempts any network connections. Crash is reproducible and persistent across reboots. Here's where the debug.log output ends. (No further errors.)
Bitcoin version v0.8.0-beta (2013-02-18 18:38:34 -0500) ... init message: Verifying block database integrity... Verifying last 288 blocks at level 3 No coin database inconsistencies in last 222481 blocks (8492 transactions) block index 4479ms init message: Loading wallet... nFileVersion = 80000 wallet 1500ms init message: Importing blocks from block database...