As for the hash rate on our site. Just like Deepbit or BTC Guild, the hash rate we display is simply an estimate and doesn't play a part in your earnings. Different pools are going to use different algorithms for estimating your estimated hash rate, add in some variance, and then you have a recipe for seeing different estimates no matter which pool you view.
However, I can tell you that our pool looks at your last N share submissions and calculates your hash rate based off of that. So, if you are just starting mining with us, or if there was a gap in your mining (eg, stopped your mining software to reconfigure it, etc), then your estimated hash rate will be a lot lower. After a few shares are submitted this will level out and IMHO start to show you a pretty good estimate of your hash rate.
Okay, thanks for the clarification, but I was under the impression that my client always shows the right hashrate, no? I'm not comparing the stats on different pool's sites, just on my own client. I'll need to double check that I use the same flags and options for your pools as I use on other pools when I get home.