Pentotype is a new web app for the iPad that lets developers create wireframes, share them with friends and collaborate and mashup and test out the user experience of new apps before committing to code.
Available for the iPad and other HTML5-enabled devices, developers can use Pentotype to quickly sketch out wireframes of their apps and test out user interaction.
It enables both viewing and collaboration for the earliest part of the app creation process. (Note, these aren’t fully realized apps that the service churns out, and there’s no code exported by the service. It’s really just a way to get a feel for the user experience before it’s all committed to code).