Yes, there is a G2 hack. I did it, but I found it kind of annoying. It might be worth it if you shoot a lot of video. I don't.
If you google "G2 hacked", you will find directions to get you started.
What I didn't like was that after the camera was hacke, the way you went into manual video mode was by entering and leaving the menu. But of course I went into the menu far more when I was shooting stills than video, so I would change a setting in the menu for a stills photo, and then find myself in manual video mode when I didn't want to be. It was easy to get out of manual video mode by switching the mode dial back and forth quickly, but annoying as hell.
However, the camera is easy to "unhack", which I did, so there is no harm in trying.
My conclusion was that I am better off saving up for a GH1 or GH2, than going down the hacked G2 road again.
By the way, the G2 is a fantastic stills camera and the unhacked video also looks awesome to me, although I am not a professional. Maybe you want to be able to say what it is specifically about the unhacked video that you don't like, before trying to hack the camera.