If I'm using cgminer (version 1.5.1) then i see a lot of:
...
[2011-07-27 18:13:25] LONGPOLL detected new block on network, waiting on fresh work
[2011-07-27 18:13:25] New block detected on network before longpoll, waiting on fresh work
[2011-07-27 18:13:38] LONGPOLL detected new block on network, waiting on fresh work
[2011-07-27 18:13:38] LONGPOLL detected new block on network, waiting on fresh work
...
That's completely normal. P2Pool blocks happen at a rate of one every five seconds on average, and that work is being pushed to the miners.