There is an increasing frequency of mergers and acquisitions in the eLearning industry. Major ones include Saba's purchase of Thinq and Centra, Click2Learn and Docent's merger to form SumTotal Systems and their subsequent purchase of Pathlore, Adobe's purchase of Macromedia, Skillsoft's purchase of NETg, Blackboard's purchase of WebCT and NIIT's purchase of ElementK.
The latest one - Plateau's purchase of Nuvosoft http://home.businesswire.com/portal/site/google/index.jsp?ndmViewId=news_view&newsId=20070221005862&newsLang=en. is an example of the large Learning Management Systems vendors expanding their capabilities to include talent management and overlap with human resource systems.
A fairly complete and evolving list of vendors can be found at http://www.trimeritus.com/vendors.pdf.