App Engine Project - FriendFeed type app using gnip & twitte

I want a very simple application built that is a bit like [login to view URL] (but on a diferent topic to stocks) and a bit like friendfeed. Signin should be done via twitter oauth and/or facebook connect - whichever the user wants to use. Site should use gnip to find content on twitter and flikr for a list of keywords. This list of keywords should be controlled by the admin user. Posts made in this application should be pushed into the users twitter stream. Youtube links should be handled so that the video is playable in situ. flikr image links shuld be pulled in. Other requirement is for a very simple cms system that has minimal markdown formatting and can include links from flikr and youtube which are then displayed as the video or the image. Whole thing should run on google app engine. Every page will need an rss feed. SEO friendly url structure required for every page. Design will be very very simple.