The closest thing to Snapchat for Windows Phone 8 is anUnofficial app on the Windows store that isn’t functioning right yet. I read the reviews for it and there are way too many complaints. Below is the link to the unofficial Snapchat app.
Rumour: Snapchat waiting for GDR3 before coming to Windows Phone
The first Snapchat app for Windows Phone! Take quick snaps with your phone and send them to your friends!