As I planned to extend our HTPC with DVB-T capabilities, I bought a PCTV Diversity Stick Solo. Couldn't find any evidence that this one is running on Linux but as it was really cheap, I thought it would be worth a try. It is a usb-stick which comes with two receivers. The stick itself is rather big and together with the two delivered antennas it is nothing I really would like to use in mobile use cases but our HTPC is not moving at all ;-).
Being a absolute newbie to the topic DVB-T on Linux, I was really surprised how it went on our Ubuntu 9.10 system. After connecting the stick to the HTPC dmesg | grep dvb shows right away that the stick has been recognized and everything seems to be green. After installing kaffeine media player - and it's dependencies as I didn't had much kde stuff on it before - and running a service scan it was there: our first DVB-T channel is presented on the screen. Easy piece of cake.
Kaffeine showed two DVB-T devices, so I think both receivers can be used under Linux, but i don't think that diversity modus is supported (using both receivers to result in one single improved input signal).
Next step is to get yaVDR running as I want the topic TV to be handled from within the XBMC software we are using anyway. Real benchmark would be time-shift recording of "Tatort" on Sunday - I can't think of the last time we managed to watch this ...