For the past 6 months or more, I've been seeing many codes hosted at sourceforge.net as well as other hosting sites "Move to GitHub". A mere Google Search with the phrase "Moved to Github" returns several results containing the text moved to github. This is very confusing for me, and I'm wondering, why exactly are people moving? Does it mean that GitHub is better or is there some special advantage I'm not seeing?
This is a symptom of a wider migration towards distributed version control systems.

Some websites which traditionally hosted non distributed VCS (eg Codeplex & SourceForge) were a little slow in adding support for DVCS (eg Git or Mercurial). So, people who wanted to use DVCS for their project were forced to migrate their projects over to the providers which supported them (eg Github or BitBucket). Github was one of the first to offer DVCS support and so naturally a lot of people migrated their code there in order to take advantage of it.

Those other websites are only now starting to catch up to DVCS (Codeplex for example now supports Mercurial & Git), but they are still a way behind in terms of features such as forking and submitting pull requests. To really take advantage of DVCS Github and Bitbucket are still the best options.
