The reason why you found an enormous but unexpected iPhone data-connection charge on your phone bill may have been discovered in Estonia.

From Cult of Mac comes word that Estonian blogger Oliver K. has discovered a bug in Safari for iPhone that will leave open a Motion JPEG video stream even if you close the Safari app. The resulting continuing stream can quickly add up to multiple expensive megabytes of unexpected data transfer when your iPhone is downloading data from a 3G or EDGE network.

And "expensive" is a gross understatement. In a blog post (Google translation) describing his testing of the bug, Oliver K. noted that a connection kept open in this manner resulted in a download of over 740 megabytes in little more than an hour. AT&T charges $0.0195 per kilobyte of data transfer when a subscriber is traveling internationally without an already-pricey Data Global Add-On plan, so a 740MB-plus download would run to nearly fifteen thousand dollars.

Try explaining that phone bill entry to your significant other.

This bug would not be apparent to iPhone users who subscribe to unlimited data plans, but such rogue streaming could put added pressure on, for example, AT&T's already overloaded 3G network.

To be sure, Motion JPEG is not a commonly used web codec, but it is used by many webcams. So, Safari for iPhone users, should you choose to view a webcam on your Apple handheld, make sure to navigate to another page after doing so. Oliver K. says that doing so is the only way he knows to interrupt the stream.

"Apple did not respond to our request for comment on this report"