Pikachu Celebrations Summer Festival
It looks like the Pokemon Center website is prepping the page for it.
Also, I came across this URL: http://www.pokemoncenter.com/Holiday-2015-Collection/b/13130362011?searchSize=60
So unless they change the URL, I think this will be the page where the Holiday 2015 items will be found.
Since this is such a short post.... and if anyone is interested
A link to what I have cataloged so far in my collection (my continual work in progress).
Also, my sales. I actually will be getting the Nebukuro items soon, but I don't know if I should even bother listing it here for sale since I think almost everyone here has gotten what they wanted.