I know they have countdown pins up to 1st April but I am not sure what else if anything is for sale yet. I did notice that someone on Ebay was selling napkins and paper cups with the 15th logo but not sure if the restuarants are using them now or maybe they we aquired!
I didn't notice any 15 year stuff in the shops but it may have been there. There were definitely 15 year napkins and some paper cups being used 2 weeks ago. I suppose they are starting to use them as they run out of old stock.
Here's a not too good photo of the cups used at the Fantasyland Breakfast