While in town yesterday, I bought a new lens for my GF1. I really llike the adapters you can find for it and the wide variety of lenses you can use on the GF1. This for me is exactly the reason why the m4/3 format is currently the best format if you want a high quality compact camera with large sensor.
It is just so much fun to look for old lenses and see the different character they give to pictures.
There are also challenges to overcome when using these lenses, like the Sigma f2.8 50mm Macro lens for MD mount I got. It is really a very nice lens but quite heavy and big on the GF1. This is not the biggest problem, it is more getting anything in focus when using it wide open at the closest distance. The DOF is so shallow that it is impossible to get any decent pictures while handholding it. This is part of the fun however for me to try and master this lens.