Grey's Anatomy Spoiler Alert - Lexi and Mark Trouble in Paradise??

We all knew it either wouldn't last or at the very least it would be a very bumpy ride. McSteamy was too much of a dog in his previous life (having an affair with his best friend's wife is definitely a dog in my book) to turn over a new leaf without incident. In early 2010 there is going to be a crossover between Grey's Anatomy and Private Practice. The crossover has McSteamy spending some quality time with his currently single ex, Addison.