Apple's 24-hour flagship retail store on Fifth Avenue in New York was closed down Thursday afternoon. The closing sparked speculations of the store being used for the filming of a 3G iPhone commercial.

Prior to the closing, Apple had said that its flagship Apple Store on the New York City's Fifth Avenue would close down entirely on Thursday afternoon and re-open early Friday morning. The company did not provide details about the closing. However, the announcement immediately raised eyebrows because this particular store has been entirely closed only twice in its whole history: For the iPhone and Leopard launches.

"We will be temporarily closed Thursday, May 29 at 3:00 p.m. and will reopen Friday, May 30 at 9:00 a.m. During this time, please visit one of our other two Manhattan locations: Apple Store, SoHo, or Apple Store, West 14th Street," a note on Apple's retail page states.

According to ifoAppleStore, the Manhattan store has been closed in the past only for special product introduction or movie productions.  The news has led MacRumors to draw a conclusion, based on unnamed sources, that the reason behind a temporary shutdown is the filming of a 3G iPhone commercial set both inside and around the store. According to MacRumors, store employees told “passersby that a commercial is being shot at the 5th Avenue Apple store."

Since there is no hard evidence to confirm the shooting of the 3G iPhone commercial thesis, we can only speculate what's behind mysterious store close down. A special product launch is the least probable explanation, especially since there were no signs or leaks that would indicate such a scenario. Filming of a commercial, however, is likely. At least if you ask us.