I am also interested in this, and have ideas...
I don't post on forums, but this is truly interesting, and I'd like to know what you've come up with since this post.
I want to access the HDMI port of my SOny HVR V1U. The firewire port shorted out and is not usable. I want a portable device to have an HDMI input, and record directly to an SD card or a fixed state hard drive. Something portable and easy to tether to the camera. I keep thinking there's an easy solution just around the bend. If it's not out there, let's invent it. I can see this thing weighing 5 oz and without moving parts. But I may be dreaming. If it has to be a spinning drive, let it be small, like SOny's $1600 60GB HDV input firewire drive. I have that as well, but it is useless to me because of the stupid firewire port shorting out. I'm kind of upset with Sony, actually. I got all that stuff to be portable, and now I'm pretty much stuck to a Black Magic Intensity card in a tower next to my camera. And that card is a great purchase. BUt most of the magic happens outside the studio.
I don't want to bring even a laptop. THis has got to be a simpler solution. THey're all but building these devices into their cameras by now.
Anyway, I hope we either find or pioneer a way to achieve this common end.