I am working on an app that is only used by a few people in-house, so I feel comfortable telling them to only use Firefox or Chrome, so I can use HTML5.
I was workin
First of all, are you using Firefox 4? HTML5 forms has much better support in version 4.
This page has details on HTML5 forms and the current bugs https://wiki.mozilla.org/User:Mounir.lamouri/HTML5_Forms
Update: If the browser does not support the HTML5 features you want to use, try Modernizr. It uses Javascript to enhance support. It's documentation has information about input types.