Loved old style shooting...with digital brain.....
1. available light shooting....no flash in E-P2
2. shoot with both eyes open....EVF or OVF
3. legacy lenses - manual focus and manual aperture...so IBIS is a must
4. non intimidating to subjects....small retro design...
5. modular...switch to compact for wifey...remove EVF and mount 17mm pancake....later switch to "DSLR" like with EVF mounted and lots of prime and zoom lenses....
Were you expecting the marginally faster AF in the Panny systems and higher res screens? I think its just a personal preference. My images look slightly different when I switch from my E-30 to my GF1 (better skin tones and deeper blues and greens in the Oly), but shooting raw takes each camera's JPEG processing out of the equation. I do like Panny's kit lenses better than Oly's but that's easily remedied too.
Originally the art filters, interface, build quality and IS were a factor.
I had the Pen1 and also a G1. Sold the G1 for interface issues and got a Pen2 to work with the Pen1.
Having the same interface is a big plus.
Now, I don't care about art filters, IS etc. I just picked up a G2. I am thinking about the GF1 because of the interface match.
They are all good cameras. They all do the job.
It's about preferences to decide on one against another.
I think the real answer to your question can't be answered yet. When the new cameras are announced, then we'll see what the manufacturers have learned. The one that listened and followed thru will get my vote.
I didn't even consider the panny. The olympus e-p1 caught my eye, the e-p2 caught my heart and the e-pl1 caught my credit card ... and its been exploiting it ever since! Why the pen range - purely aesthetics!
Switched from a GF1 to E-pl1 (and e-p1 for my wife) primarily for IBIS, which I am used to also being a Pentax dslr user. I got tired of missing shots I was used to getting at slower shutter speeds with my Pentax gear. IBIS is great for adapted lenses as well.
In fact I chose the Panasonic over the Olympus but i think my answer could help any who were on the wire. I did a ton of research and realize both would fit my need. I was aware of the strengths and weakness of both. When I got to the store the two packages they offered were very similar in price but the accessories were a slight bit different. My first impulse was the Olympus as its looks rocked. When I picked them up I fell in love with the Panasonic, not that it was a better camera but it fit my hands perfectly while Olympus was not as good of a match. So in the end is says more about the size of my hands than anything else.