In reply to pauldr:
Reading through the article and from experience.
The gx1 has better ISO ratings (for mines) battery life lasts longer and is smaller.
The g3's main advantage is the built in viewfinder, and the bulkier body can mean people with bigger hands find it easier to handle, and a tilting screen. But that's personal preference on if you'll even use it (i love it on mine, but I like low angle shots)
And as an owner of an olympus pen I can vouch that a smaller camera means you take it out more
Don't know if that helps! FYI Panasonic have a really nice video mode
