What is the plural of "BlackBerry" (as in the handheld device)

Solution 1:

I appreciate @senderle's choice to consider the New York Times as a source for common usage.

However, I found the "proper" answer in a BlackBerry Branding Guidelines PDF from 2007 (page 5):

Avoid using the RIM Marks generically, as nouns or verbs and do not use them in the plural or possessive form.

and

3. Do not use the RIM Marks in plural or possessive form.
   ✓ BlackBerry® smartphones
   ✗ BlackBerrys, BlackBerries, BlackBerry’s

This is in agreement with what some other answers have suggested.

Solution 2:

I would write Blackberries rather than Blackberrys. The latter looks like a terrible spelling mistake. For most situations, altering the brand name in this way won't matter.

However, if you're preparing a formal document and need to use the exact trademarked name, then you'll have to use a circumlocution such as Blackberry devices or Blackberry phones.