Sorry I didn't see this till now. Drtooth, I gladly answer your question.
We're more of a commonwealth, or freely associated state. Since this is directed at holiday celebrations, I'll answer that facet of the relation between the two countries.
With regards to Thanksgiving specifically... We do get the day as a holiday, and most government funded educational institutions like the University of Puerto Rico and other private schools that are in line with the US schooling system also give the Friday after as a free day. It's a 4-day weekend.
As far as the Thanksgiving lunch/dinner itself, it's rully up to the people themselves if they want to celebrate it and make a traditional T-Day feast or not. My family always gets together, though that's been during the last ten or so years.
Hope this helps, LMK if you have any other questions.