We just published a must see paper written by Patrick Tisseghem of U2U, Mike Fitzmaurice, and heavy consultation from Mike Ammerlaan:
Have you wanted information on how to package Web Parts, event receivers, list/feature/site definitions into solutions? How to deploy those solutions from a development environment to a test environment into production? How application assets deployment is different from content deployment? How to push a new version of a Web Part/feature/application page out to a site that has the old version already in production?
This paper covers it. Go get it!
how can we save pptx files as open xml and retrieve slides back programitically
You can find a couple articles with code sample and videos here: