If you don’t need the video features of the GH1 be smart and buy the G1. It costs you far less and the image quality is more or less the same as the GH1. Amazon.com is selling the blue Panasonic G1 with 14-45 mm lens and the red Panasonic G1 with 14-45 mm lens with heavy discount.
If you are looking for small sized lenses a good option is the classic FourThirds Olympus 25mm f/2.8 Pancake Lens. You have to use the adapter ring!
The Panasonic 45-200mm f/4.0-5.6 is the only MicroFourThirds cheap tele zoom lens available to date. It is a good lens for his price!
I found ONE single Fotodiox Olympus OM – OM 4/3 Adapter for my old E-420.
Having some M-mount lenses I seeked Novoflex Adapters:
Amazon Germany has finally the full range of Novoflex Adapter. In Amazon US I only found the Novoflex Adapter to Mount Leica M Lenses on a Micro Four Thirds. And amazon UK has only two Novoflex adapters.