Of possible relevance to anything to be done on Scilly is the Hacking the Himalayas series by Xeni Jardin and aired on the US’ National Public Radio. Their site allows you to listen to all four of the series’ shows online.
Getting online for Wicken-Archaeology.org.uk was tough, and that was all taking place in a backgarden in Northamptonshire; we relied upon sporadic 3G and WiFi connections. In remote areas, more reliable, creative, connections will need to be established: More bandwidth, less latency.
Whilst the Hacking the Himalayas may not be directly analogous (to what, I don’t even know yet), it’s an example at least of networking ideas as well as technology. As a side note, I’ve set up a Wireless Distribution System at home based on the fantastic OpenWrt.