Yes, they're safe. (You should make sure to keep the old wallet just in case, but since your transactions were done yesterday and presumably many people will re-run all lost transactions, it shouldn't matter.)

1) If you run a mining pool or are mining solo, and have upgraded to 0.8, downgrade to 0.7

2) If you are a normal user, do not perform any important Bitcoin transactions until you get the all clear.

3) If you are a pool miner and you know your pool has not downgraded, stop mining.

4) If you performed any transactions recently, be warned that you cannot rely on them.