Via the dpreview Micro Four Thirds Talk forum.

The South Korean manufacturer Dicain obviously has a very nice extension grip for the E-P1 in their program. From searching the webs, they seem to be well-known for their battery and shutter grips for various DSLR models, but this E-P1 grip seems to be a more recent (and less known) development of theirs.
The grip is available in either black or silver and plugs into the tripod mount, covering the whole baseplate of the E-P1. The actual grip extends halfway over the E-P1’s integrated grip and looks like it could offer substantial handling improvement, especially when using longer and heavier lenses, such as the Lumix 45-200mm zoom or adapted Four Thirds lenses.
The retail price is ₩ 79,000, which translates to roughly € 53 or US-$ 64. I am not certain, though, if it can be ordered from outside of South Korea.

It would be interesting to hear from someone who owns and uses this grip, as to how handling is improved and how the grip’s build quality is. At least it looks nice