Well guys and girls, just before I'm off to Portugal I can offer you some good news.
ForTheRecord servers can now be used from XBMC running on Mac OSX, Linux (and of course Windows too

).
I made a series of screenshots that you can find in this album here:
http://imageshack.us/g/694/xbmcftrosx01.png/. Be patient, as I'm running my virtual machines at 1900 x 1200 and the screenshots take some time to load from imageshack.
Since I couldn't find an easy way to add captions I'll just list here what you see in the pictures.
XBMC on Mac OSX, Live-TV highlighted in the main xbmc screen, showing FTR recording a show;
XBMC on Mac OSX, Channel list view with live-tv playing in the preview pane;
XBMC on Mac OSX, EPG data showing channel vs time grid;
XBMC on Linux, Live-TV highlighted in the main xbmc screen, showing a scheduled FTR program;
XBMC on Linux, ForTheRecord addon settings/configuration dialogue;
XBMC on Linux, Channel list view with live-tv playing in the preview pane;
XBMC on Linux, Live-tv playing in the full windows;
XBMC on Linux, recorded shows dialogue popped up over a playing recording;
As with the Windows RTSP version, channel zapping is not working while viewing live-tv. As a workaround stopping viewing live-tv (press 'x') and starting live-tv on a different channels works fine :roll:.
When I return from the vacation in Portugal I'll start looking into the zapping issue. Unless I can't resist to work on porting it to iOS and AppleTV2...
Cheers,
Fred
(signing off until the 2nd half of August 2011)