Unfortunately, for whatever reason, the 2 Gbps service doesn't allow for (or didn't, when I looked into it) the use of your own routing equipment -- you have to use the wireless router that they provide.
The 5+ Gbps blog explicitly mentions being able to use your own routing equipment, so that's a promising sign. I'm not in the regions that Google Fiber explicitly listed, but I'll be keeping an eye on future announcements.
The ONT on a stick (aka SFP) plugged into the Technicolor manufacturered router Google provides can me moved to other routers. The difficulty is that instead of negotiating at the usual 1 or 10Gbe, the SFP negotiates at 2.5Gbe (commonly known as Multigig). There's next to no hardware on the market that supports Multigig, this makes it seems like no other equipment works with Google's service.
I wish they just went straight to SFP+ but I'm sure there are good reasons why they did not.
I assume there's no reason that you can't use a 2.5G copper SFP module to connect to this also?
2.5Gbps SFP is technically a standard, but since it came out after SFP+ has been standardised no-one really bothered to use it.