Seen them in trees in Texas to go after roosting turkeys.
When young turkeys are spooked, they fly into trees & stay there, heard of bobcats going up after the young ones as well.
I cornered a young-small bobcat one day & it went directly up the nearest tree as well. /ubbthreads/images/graemlins/smile.gif It stood there on the limb looking down at me, & it's momma came back & sat down & watched me....I resumed by fence building, & left them in peace. /ubbthreads/images/graemlins/grinning-smiley-003.gif
As far as seeing them just climbing a tree for the hey of it, or hanging out in a tree, I've not encountered that myself.
Barry