It should also be possible to permanently dismiss the update notification. It's extremely annoying when working with portable, customised installations of sublime - every time it runs, you get the update nag screen with no way to stop it. Updating is not a straightforward process in ST2 if you've customised the installation, which I have with one of my portable installs. Updating potentially breaks plugins, so this is something that one might want to do in his/her own time, if at all.
Especially with Sublime 2; The only big "issues" I have with ST2 - that if rectified would inspire me to update - are the inability to hide the Linux menu (same in ST3) and punctuation which breaks across lines on the display (giving the appearance of orphaned full stops at the left edge - fixed in ST3). Neither has been addressed in 2.0.2, so I have no interest in upgrading personally - I'd rather save the hassle for if/when I upgrade those installs to ST3. As an aside, I've also read here about possible issues with the upgrade, another reason to delay upgrading.
There should be a setting "update_notifications" set true by default, which can be overridden by the user in the case where s/he does not want the notifications, especially so for paying users.