Are there Ethereum API wrappers?
Not yet.

We've just revamped the server side RPC internals in develop and are still ironing out some quirks. I can imagine we would soon-ish start working towards the directions of providing some Go client APIs, but we're not there yet. If you just need a few specific ones, they are relatively easy to implement (here's a few we needed for a hackathon last week https://github.com/gophergala2016/etherapis/blob/master/etherapis/geth/api.go).