I haven't heard much about the audio capabilities of the 7D, but I assume it won't be a prime device for quality audio recording, especially without dual XLR inputs. So I figure the audio would need to go somewhere else.
I'm planning on using a zoom h4n for recording in conjunction with the onboard audio. Bought one on Ebay from these guys http://myworld.ebay.com/unique_squared_inc/ based on recommendation from another poster here. A lot of the Gh1 users have been using it with success.
Yea, it's really great for a small mobile solution. I have a DP friend who is in the reserves and just got called to Afghanistan, he will be shooting special training videos and combat action stuff with a gh1, zoom h4n, senn G2's, two tram tr-50 lavs and a sennheiser me66 all in his backpack with war gear
I like my H4n for quick SFX audio, but for double-system audio I think the Marantz 661 is better suited. (debating getting one myself, or just going all out for a SD 702T)
It is more expensive though, just depends what budget you're looking at. The H4n is certainly a great deal just as it is.
The H4N gives incredible results. Don't get the H4, it has a terrible button/menu layout and is very particular about which cards it will work well with.