Oh Dear
I don't have a GF1, my E-P1 has been stolen by my son, and I only have 5.4 of the DNG converter.
. . . . . but I am a sucker, so I've dug out some E-P1 files, and I'm downloading the DNG converter, and I'll give it another go.
The trouble is that Aperture does not recognise the lens corrections. I'm guessing they are really going to have to get to grips with this, and there will be an update soon - which will probably cover the other similar cameras like the d-lux4, the lx3 and the G1 . . . but I don't know (just hoping really).
One thing I can say is that Aperture will recognise DNG files which it doesn't have camera profiles for (the Leica M9 is a perfect example). When they do include camera support you can apply it or not. The basic DNG support may not be complete, but it IS good - I've fiddled with C1, Lightroom and Aperture with the M9, and come back to Aperture as providing the best combination of quality and useability. Converted files from both the Sony A900 and the Olympus E3 worked well with aperture before they had full support.
Okay - while I've been rabbiting I've downloaded 5.5. . . . . .
I'm sorry for the bum steer . . . it simply doesn't work. (I was sure it did with 5.4, but perhaps I was mistaken).
So the choices are to shoot jpg until Apple get their act together, or to download a trial of Lightroom to use in the meantime.
Apple really should get their act together over this, it must be losing them business every day . . . it makes one wonder about their commitment to Aperture.