The other half of the Sugarcube Corner couple, Carrot Cake seems like a good guy, although there's not really that much to say about him. He's enough of a Ponyville regular to make the new group scene in the opening credits for Season 4 (judging by promos that the Hub have been showing), and I can't really argue with that... The Cakes are Pinkie's supporting cast, even if they aren't as important to the show as, say, the Apple Family, and really they're a part of what makes Ponyville Ponyville.
One wonders if the inclusion of characters in that credits shot can be used as evidence to suggest some importance in Season 4... Regardless, I feel a certain cheerful teacher was snubbed.