An article on SDR, and no mention of the RTL2832? :(
All this talk of low transmission at many frequencies reminds me of ultra-wide-band wireless... whatever happened to that?
I think SDR is a really good idea, but has two major stumbling blocks: 1) it makes government control of the airwaves trickier (IE removes some technical obstacles to misuse), and 2) major military contract failure involving emergency/terrorist multi-agency communication.