There is an Orlando Chihuahua Meetup group. http://www.meetup.com/OrlandoChihuahuas/
While I don't have Chi's of my own yet (although I want one sooo bad!), my mother in law has two and she's looking for someone with chi's to meet up with at a dog park here. What part of Orlando were you looking at?
The park we usually visit is the West Orange dog park in Winter Garden.
Edit to add: There's also an Orlando Small dog meet up in Orlando too. http://www.meetup.com/small-dogs/