In fact, it used to be the standard script for coinbase transactions: miners would actually use the script instead of the hash160 form for the generation output.
It still seems to be the default, although perhaps modern pools are using the hash160. A quick survey of recent blocks showed at least one using just the pubkey, though.
As for whether it's standard, I don't know.
It is recognized by the script solver, so should be accepted as a relayable tx type. The comment even says pubkey-only is "standard", and the more familiar type is "Bitcoin address"*.
Feel free to correct me; you two know your way around the code a lot better than I do.
* Trivia I stumbled on: In the earliest commit it was "short account number".
