Do I need to prune or just let nature take its course?

Yes.

Jon not in a mood to deal with newbies?

Yes is correct though, you can prune it or just let it grow. More info is needed, like in a pot, your zone, how big you want it to get, etc....

Hi Bugmagnet,
Depends on the size of your tree :) .
Which USDA zone are you in ?
I have a 6 years old tree that I never pruned myself except for removing the suckers at the base.
But, in my Zone 7, I get free style pruning during the winter from winter die-back . Especially in the harsh winter of 2012 ... my trees got a special pruning that lowered their size...
If your tree has too many branches, prune the ones going inward and space the branches on the trunks .
If you show us a pic, we can better help with the haircut  ... I bet punky is the trend this year :P .