Just a little "by the way" for other Joggler users:
I've had a spell running both O2 stock firmware + PMJ ("Pimp My Joggler") and Stephen Ford's Ubuntu Netbook Edition 1.3a on one of my Jogglers (see http://www.joggler.info/). I use the Joggler at the moment primarily for radio but in an ideal world would have iPlayer for Listen Again too (hence the attempt at Ubuntu). The O2 stock firmware/PMJ is definitely more stable when running over several days than the current Ubuntu build - I don't know why yet, I just find apps won't start etc. That's not to say the Ubuntu built couldn't be made stable enough, but I expect that OpenPeak/O2 have spent some time tweaking the stock Linux OS.
Therefore, for the requirement of building a robust HA app that doesn't need tinkering with (is there such a thing?!), I think Kevin's approach of building a xAP app in Flash on the stock OS is the way to go.
Simon