If it's more excitement than submissive behaviour, he may grow out of it - in the meantime keep every greeting very low key, and have others do the same - even just ignoring him until he's calmed down a bit.
Has he been through any training classes? It sounds like he could really benefit from being around other dogs in a structured environment, and learning will increase his confidence ALOT too. Often very excited play/greeting behaviour is also somewhat submissive and could indicate a lack of confidence - acting very puppy-like instead of adult.
Try teaching him an alternate behaviour for greeting people - like when he calms down (and you're all ignoring him) have him sit, offer a paw, hold something in his mouth, whatever might work with him.
It might not hurt to have a quick vet check, too - sometimes the (I can't think of the name of the muscle that controls urination) - whatchimacallit
is somewhat weak - there are some fairly benign meds you can give short term to remedy that.
But barring any medical issues, I think a fun obedience class will really help! Actually structured obedience classes will benefit almost any dog - and he's probably pretty smart and high energy. Mental stimulation helps wear dogs out too!