Supply will likely meet demand for a while now, especially with one more wave set to release next week. Well worth it, but not a perfect solution as some HDTV's won't display a 240p signal. I have three HDTV's in my house, and only one is compatible (luckily it's my big screen in the living room). Also, from what I've read on forums, some TV's that will work with a Genesis won't work with a SNES.
I'm looking forward to their upcoming Dreamcast cable. Even though Dreamcast can natively output RGB via VGA (which looks great on a modern HDTV), not all games work when the VGA cable is connected to a Dreamcast. Certain games will only work via A/V or S-video (including my favorite DC shooter "Gunbird 2"). The new HD Retrovision cable is supposed to be compatible with all games.