Update 4.2.2 has been slowly rolling out Over The Air to devices but many people haven't received it yet. IF you want to force your device to download it, do the following:
- Go to Settings -> Apps -> All
- Find Google Services Framework App
- Tap on Force Stop
- Select Clear Data.
- Go to Settings -> About Tablet -> System Update
My device wasn't receiving the update until I performed this little work around.