Seth Godin, a well-known marketing book author, speaker, marketeer and blogger, has a good piece about why joint ventures fail often and why licensing is the better alternative. You’ll find it here:
http://sethgodin.typepad.com/seths_blog/2009/06/why-joint-ventures-fail-so-often.html
Joint ventures might work well in plain B2B environments.
When you are marketing products or services to consumers, it gets difficult. Like for SonyEricsson, Fujitsu Siemens, Sony BMG, etc.
A joint venture that seems to work in the consumer area is BSH Bosch Siemens Hausgeräte (home appliances).