Hi Rachel,
Unfortunately, Princess Tiana's Showboat Jubilee ended its run at the WDW MK on January 3, 2010. It was a really cool show and I was fortunate to be able to see it. I am sad to see it go. The good news is that you can still meet Princess Tiana and Prince Naveen in the Magic Kingdom near Ye Olde Christmas Shoppe in Liberty Square. There are several meet and greet sessions each day that last approximately 40 minutes each. Be sure to pick up a schedule of events for exact meeting times when you enter the MK.
I have not personally seen any IM merchandise in the parks. Your best chance for finding any (if there is any) is at DHS near Playhouse Disney - Live on Stage! I know that there is merchandise available on the IM website - click
here to go to their official website.
While I am not 100% positive, I would be willing to bet that the kids in the audience for the filming of the Christmas Parade were given the IM jumpsuits to wear during that portion of the filming - not sure if they got to keep them or not. It makes for great fun TV and I'm sure the kids had a blast being able to be a part of the magic!
Please let us know if you have additional questions! We are happy to assist.