Do it in any language you want to learn. The prize is knowledge!
Some of the more interesting would be Erlang, Elixir, Lua, Rust, Go, Haskell, Ocaml, but also anything more exotic than theese (OTOH an PHP version would be really crazy exotic for this kind of an app).
Connects to gtalk as an xmpp or hangouts (protobufs) client. Connects to my prosody as an xmpp component and forwards messages to my one single account.