Hacker News Reader

10G no, but all 1000BASE-T NICs require autonegotiation for 10/100/1000 to be compliant.

NICs maybe, but there's a whole heap of cheap home switches and hubs that don't support 10BaseT. I know this from experience.

I've also experienced some quite expensive Juniper DC switches not supporting anything below 1Gbit. Fun times.

Some ISP core stuff too.