Update on this item
The devolo "highspeed" homeplug gizmos are pretty good. There was a little buzz of excitement when the idea of power cables being - well, just power cables - suddenly lurched to the left by some distance and the idea of "just fat, slow cat5" snuck in next door.
The 85Mb/s claimed by Devolo isn't exactly electrifying (heh?), but that's ok, I only recently moved out my last 10Mb PC (100MBit still feels so fast). Anyway, it seems to move standard resolution movies (about 700MB or so) to the XBMC ok, and that's the one my girlfriend will be upset about. What the Devolo kit doesn't seem to is actually give me decent network throughput.
I did some testing using netcat - 6Mb/s! Ok, so the power/network isn't ideal (old wiring, too many power strips, etc.), but the "informer" app says I'm getting about 50Mb/s, so long as there's no actual traffic. If I actually ask the network to carry some traffic (as with netcat), the informer app says the devolo kit drops to 20Mb/s, while I'm only getting 6Mb useful throughput.
If I can improve the wiring setup (attach the devolo kit to it's own sockets rather than on power strips), I'll retest. So far though, in my little flat, with too few power sockets, in odd locations, the results aren't too encouraging. Do I currently feel like shelling out for the newer 200Mb/s model? Not really.
Maybe 802.11n is the next step - even with the thick walls here...