Google is using remote memory accesses rather than TCP for at least some classes of traffic (e.g. a caching system). They've been publishing details about how it all works too.

Also, they have a transport (Pony express) developed specifically for RPCs, rather than byte streams or datagrams.

Links: https://research.google/pubs/pub51341/, https://research.google/pubs/pub50590/, https://research.google/pubs/pub48630/, more generally https://research.google/pubs/?area=networking