Integrate pdf.js as PDF viewer http://andreasgal.github.com/pdf.js/ – (optionally also a "Documents" app where all PDF files are shown)

More info:

Basic scenario is to create default behavior for pdf filetype. This should trigger displaying of chosen pdf file (as a overlay layer).
Following tasks should be fulfilled:
* remembering last opened page
* create focus arena (make background gray) 

Ideal scenario is to create entire book app with features:
* shelf display (ie: http://touchreviews.net/wp-content/uploads/2010/01/Kobo-iPhone-eBook-Reader.jpg) (nice to have)
* bookmarks (must have)
* book fragments sharing  (nice to have, might be hard)
* in book search (nice to have, might be very hard)

for last two features i'm willing to extend deadline for 3 days, for shelf display i'm willing to extend deadline for 8hrs