The trendy "flash mob" phenomenon has arrived in the Twin Cities. "Flash mobs," a sort of performance art in which a group of people organized over the Internet mysteriously gather in a public place, do something strange and then quickly disperse, have been occuring lately in New York and San Francisco. Last night, a flash mob was created at the Mall of America in Bloomington. The details of a flash mob activity are kept secret until just before the event begins. Luckily Minnesota Public Radio's Nikki Tundel (tun DELL) was tipped off to last night's gathering and went out to the Mall of American to check it out. That is MPR's Nikki Tundel (tun DELL).