Are there any Android devices that cannot be rooted? I bought a new Galaxy Mega and it seems nobody has figured out a root method for it yet.  Are there devices that have been on the market for more than a few months that are not rootable?
Wikipedia provides a few answers:
http://en.wikipedia.org/wiki/Android_rooting


  In the past, many manufacturers have tried to make "unrootable" phones
  with harsher protections (like the Droid X), but they're usually still
  rootable in some way, shape, or form. There may be no root exploit
  available for new or recently updated phones, but one is usually
  available within a few months.


But that's the past. 


  Only a minority of Android devices lock their bootloaders—and many
  vendors such as HTC, Sony, Asus and Google explicitly provide the
  ability to unlock devices, and even replace the operating system
  entirely.


So shortly speaking, no worries, if there's no root yet, surely there's one to come out soon.