I already own a Sigma DP1 so the slower AF i am used to and tbh doesn't bother me in the slightest, it's still faster than manual so I dont see what the fuss is about, I would hardly choose one of these for it's action capabilities, so that not a deciding factor.
I wouldn't worry about the AF speed of the Oly's TBH.
The AF speed of the E-P1 is fine (I friend with a Pan G1 tried the E-P1 and stated it seemed faster than his G1, and the Oly had much less shutter lag).
And people don't seem to complain about the G1's AF Speed or Shutter Lag (and not many '5D2 owners' complain about the 5D2 AF's), so I guess it depends on what you are used too.
Obviously the GF1's is faster/better/etc - but depends on your requirements.
Continious AF on the Oly is pretty poor though, which for me it's really a worry. The only thing I'd (notice I said 'I') really use 'Continious AF' on this style of camera is Video, but TBH - unless the camera can attach an external mic (or you video without sound), then Continious AF makes ar too much noise to be useful (which I have read is a problem with the E-P1 and GF1)
The E-P2 does have the option to attach an external mic (like the GH1), but I'm not really sure I'd be bothered to attach an external mic for quickly shooting some video of the kids, as that's the only time I use video really.
The E-P1|P2 with the kit lens is more compact than the GF1 due to the Oly lens design, which for me is a real selling point. Another selling point of the Oly is the Body IS, but not really a talking point unless you plan to have a 'system'.
If you are a prime person, theres no difference in size.
The built-in flash, faster AF, usable Continious AF and 20/1.7 seem to be the advantages of the GF1.
Not sure about the Ricoh GXR for me - as I don't think I'd want to have to buy a image processor, sensor and lens in one. I understand why they have done it, but to me it seems like it's been done to provide the best IQ for a small camera, rather than to provide an affordable small camera with great IQ.
i.e. it's about size and form factor, rather than cost.