The first is the First Annual SIGMOD Programming Contest (via nconway's blog). You need to create data structures to index a generated data stream (in fact streams, because multiple streams are presented to you in parallel) and perform operations on them (insert, update, query).
The second one is the Cisco Developer Contest (link from Ubergeek.ro). The first deadline is the
12th January 2009 27th of February. Apparently you can put small computers running Linux in some of routers and they can run applications + they can interact with the router. Check out the video here. The prizes seems substantial ("total prize pool valued at US $100,000").