Adobe have just released a app for comping wireframes and mockups directly from your iPad.
Comp is part of the Adobe Creative Cloud subscription package, and is their first mobile app to integrate with Typekit, so you can use all your favourite fonts, as well as use layout assets from your existing Adobe Creative Cloud Libraries.
Once you’ve created a wireframe with Comp, you can then create a package to use via your preferred desktop layout app such as Photoshop, Illustrator or InDesign. Adobe have created a set of gestures that will then be translated by the app into various layout elements, so with a little practice it should be a pretty intuitive app to use.
You can download Adobe Comp now from the App Store.