The bandwidth of CATV is so high that it's wildly impractical to transfer it over air with any sort of consumer level radio transmitter- best you can really do are solutions that pick one channel and transmit it.
I have a really cool device called SlingBox on my TV- it hooks up to your cable box/DVR (or uses its own internal analog tuner) and puts it on the internet. You can go anywhere in the world, pop open your laptop, and watch what's on your TV at home. It's compatible with wifi, and allows remote control of the cable box/dvr/tv through a virtual remote control and IR modulator. (When my [spoiled rotten] kids are crying that their show's over and they want me to put on another show from the DVR, I can be a lazy-ass and sit at my computer, pull up Slingbox and remotely control my DVR to put their show on.)
So, in short, this would still not let you wirelessly stream CATV to a new location. But if you had a computer in that location, you could watch TV on it through your home's wifi network.
