DART is not Linux, it's a proprietary OS that is based off of another OS. The only piece of the Celerra that is Linux is the Control Station.

Also based off this comment in the article, EMC has been working on a stealth project with VMware over the past year, according to EMC President and CEO Joe Tucci. The project includes building parts of VMware's virtual machine technology into EMC's storage management software. I expect their motive for this purchase it to extend the functionality of their products, such as Control Center and its affiliated products. Course I haven't been able to figure out exactly how yet.