I have not been able to update to PB3 and now unable to update to PB4 because the App Store cannot find the updates. I have even tried using the terminal command softwareupdate -l to no avail. Is anyone else having this issue? I downloaded the installers from the developer forums for PB4 and tried making the appropriate folder within /Library/Updates/ also to no avail. I've tried deleting various .plists associated with OS updates as well. Really not sure what to do at this point.