Holy moly!
I’ve been using a pair of Netgear XE104s to extend our network to the living room. They connect using mains electrical power, and have worked fine for a couple of years.
This morning I replaced them with Netgear XAV5501 AV+500 adapters, which claim to work at gigabit speeds. So I ran a small test, sending a 30mb file to the mac mini in the living room using the XE104s: 28 seconds. Same test with XAV5501s installed: 4 seconds!
Brilliant!
Here’s a link to a proper review, and here’s the Amazon UK link if you want to buy.