Recently had a real estate agent state that he was going to solicit all the leads he was given by the brokerage and start a new brokerage. Any recourse against this agent?

Depends on the contract between the agent and the brokerage. Most contracts would prohibit such an action. If there is no contract, then there is probably no legal recourse. What the brokerage can do is contact all the leads and inform them that this agent is unethical by trying to steal the brokerage's contacts and suggest this is not the type of person they want to deal with.

I agree, I would assume, there are strict non compete contracts, that is standard in the real estate industry in America.

There is also the issue that the leads should be people who have signed agreement with the one broker, and can not just change brokers anytime they want.

Leads don't have to be people with whom contracts have been signed. They can be any caller, anyone who signed into an open house, anyone who contacted a website.

I wouldn't worry about it too much. Does this agent even have a broker's license yet? Aside from the legality of any contract he signed with his/your broker, he's blowing hot air and full of self importance. Potential buyers don't 'follow' agents when they move around, at least not more than a tiny number.

One would assume the brokerage will stop giving him leads if he doesn't bring them back to the brokerage. Are you a part of the brokerage? If so tell your boss. If not why would you care if he wants to go out on his own and steal clients? It's done all the time.