While Dell pleased some with the addition of more n-Series machines that won't come with preloaded Windows, it seems they will not be going forward with plans to include preloaded Linux. For a variety of reasons, such as the incredible amount of distributions and various opinions on what should be included, they are backing away:

Although Dell is dancing around the idea of reintroducing Linux desktops and notebooks, the computer maker said it won't make a move until one of the competing flavors of Linux emerges as a business favorite. Dell now maintains that it doesn't want to pick one Linux distribution and alienate users with a preference for another.
There is probably a lot more to it than that, but overall it is not a surprise. Some are going so far as to claim that Dell is caving under pressure from Microsoft. Dell did not directly respond to that accusation, and instead pointed out their corporate offerings, such as Novell's SUSE.