Hey Adam, we haven’t yet built this into our forms (although we will soon, I promise) but I’ve put together a knowledge base article outlining how you can use a little bit of javascript to accomplish what you’re looking for:

http://support.unbounce.com/entries/4…

A number of other threads on Get Satisfaction have popped up with the same request, so we’ll make sure we get it built in to Unbounce as soon as possible.

Hope that helps,

Carter