Unless PPcoin has demurrage, this guy is scamming people BECAUSE every hour or so I keep losing coins from his pool. last night I had left it at 2.8X something, later I visited it was at 2.75 now it's 2.69 ppcoins.
This is due to the changing hash rate/difficulty of the PPC network. As the network hash rate goes up the block reward goes down. The number shown on the pool is how much you get if the pool finds a block right now. The reverse will happen when network hash rate drops... you will see your reward going up faster than it is now and it may even go up if you are not even mining atm.