Are we having another split? ...
The only way to tell whether you're on a split is if the displayed pool hashrate is significantly less than what it actually is, which is currently ~200GH/s. ...
Thank you for the answer forestv. I'm getting ~200GH/s so I guess I'm still on the main pool.
...
2012-02-12 02:59:38.372000 P2Pool: 17350 shares in chain (8969 verified/17354 total) Peers: 30 (0 incoming)
If P2Pool's data directory was removed, it has to redownload the sharechain, and it can only verify half of them then. You have to wait a day for them all to be verified. If another sharechain is coexisting with the main one, your client will download both and might display about a quarter as unverified... But that's not the problem here.
This instance of p2pool had an empty data directory, so your explanation makes sense. Thanks again forestv!