I bought both Proto, PS Touch and Kuler, as a designer I thought this would be handy, however I understand now that I need Photoshop CS5.5 for accessing the files from PS Touch (I got PS 3), but how about Proto? Does the file saved consist of CSS files etc?
When you upload a Proto file up to the Creative Cloud it creates a .zip file that, when un zipped, contains .css files and .html files of each page created in Proto, along with .gif files of any assets you have used (images for example).
There was another explanation of this here: http://forums.adobe.com/message/3971635#3971635
Hope that helps!