Having trouble updating to the new versions of GarageBand and iMovie for iOS, or seeing the Twitter for Mac update download over and over again in the Mac App Store? You're not alone; we've seen several reports of issues getting apps updated properly, starting earlier today, and it's hitting our team as well.
No word yet about what might be causing the issues, but hopefully they're just transient growing pains; we'll check again in a couple of hours.