I've found very interesting product, thanks to advertising on this site.
Avcast system (
http://www.homeautomationnet.com) allows to link all the video sources and TVs at home.
There are 2 major components - CableCaster (splitter/combiner/amplifier) and MediaCaster (RF modulator).
The question is - are you aware of any similar solution where modulator supports PAL rather then NTSC?
Thanks!