Google open sources its updater: Omaha
The virtual owner of the web, Google has released its software update framework, codename "Omaha" under the open source license. What this means is that you can use the update framework in your own Windows apps. Since its being used in Chrome and Google Earth, you can be sure abot its robustness.
So if you have a windows application that needs updating, look no further than here. Detailed blog post here.
P.S: For Mac OS X, try Update-Engine
Openslide – Open source alternative to slideshare
Just a quick heads up. One of the nice guys in India has floated a open source project to create an alternative to http://slideshare.net. The project is in the planning stage, so if anyone wants to help, you can contact the admin.
Read more about the project, straight from the guy who started it on his blog here
The sourceforge page is here