Snapchat has had plenty of security concerns of late, and the company is keen to be seen to be reacting these issues.
As part of that plan, Snapchat-like apps on the Windows Phone store have been erased from existence. The company says this is about protecting the security of users who may be giving their information to smaller outfits who may not be entirely legit but the reality is that it just leaves people without an app like Snapchat, given that there's no official version on Windows Phone yet.
One possible reason for this would be the arrival of a Snapchat app in the near future but for right now there's been no official annoucement, though there could be a framework released which would make knock off apps more secure in the future.
If you want to Snapchat, you'll have to use Android or iOS for the forseeable future.
More as we get it.