For those that live on the cutting edge by watching the nightly builds of the 2.0 alpha you have been cutoff from automatic updates by an unfortunate bug introduced in a recent build (a9401). You can update by opening preferences (
⌘,) and switching to the Software Update tab (
⌘5). Here you will notice that the last check was a while ago and can manually check for an update by clicking "Check Now". After updating to a9409 or newer it will again check automatically for updates.
If you are using the "Normal Releases" option in this tab this bug does not affect you.