The doctors of Seattle Grace-Mercy West and Oceanside Wellness will be racking up some more frequent flyer miles between L.A. and Seattle later this season.

Grey’s Anatomy and Private Practice will cross over again in early 2010, with former lovers Addison Montgomery (Kate Walsh) and Mark Sloan (Eric Dane) popping up on each other’s shows, the network confirms.

The crossover will begin with Addison heading to Seattle for a surgery on a young patient (Leven Rambin of Terminator: The Sarah Connor Chronicles). Sloan will then travel to Oceanside for followup. We’re going to assume that a healthy dose of commentary on their past will be part of the action as well.

Grey’s Anatomy and its spinoff have made a semi-regular habit of crossing into one another’s worlds since Private Practice began in fall 2007. The two shows did a two-week crossover last February, and Walsh also made an appearance on Grey’s in May 2008. James Pickens Jr. did a cameo on the Private Practice series premiere, and Chandra Wilson guested as Bailey earlier this season.

ABC hasn’t set an airdate for the latest crossover, but it’s likely to run shortly after the new year.

Source: Zap2It