The Apple Store is back up by Philip Elmer-DeWitt @FortuneMagazine June 19, 2011, 9:31 AM EDT E-mail Tweet Facebook Google Plus Linkedin Share icons The yellow Post-it is usually a sign that something new is coming [UPDATE: The store came back up shortly after 6:00 a.m. EST Sunday. If there were any changes, I can't see them.] Sometimes Apple AAPL takes its online store off-line for cosmetic changes — like maybe a Father’s Day sale. Sometimes it’s to clear the decks for a new piece of hardware. What that might be, we can only guess. Among the products due for an upgrade: Airport Extreme and Time Capsule. Supplies have been running short and last week’s update to the OS X Airport Utility made references to next-generation models. MacBook Air. Last refreshed in Oct. 2010, a new version of Apple’s lightweight laptop is widely rumored to be in the works. According to Deutsche Bank’s Chris Whitmore, however, Apple is holding it for the release of OS X Lion, due in July. Cinema Display and Mac Pro. Not much chatter about either of these, but their last refresh was July 27, 2010.