does anyone know of a Go client?
It probably does not (yet) have the generated client for cloud bigtable checked in (but I'm sure it will), but you can always use it to generate a client. You pass it the API to use on the command line, it will go fetch the docs it needs to make your client, and put its source where you tell it to.
> To access Cloud Bigtable, you use a customized version of the Apache HBase 1.0.1 Java client.
go get google.golang.org/cloud/bigtable