In 2004, the Vermont jam band pulled a "Seinfield" and quit at the height of their popularity, killing the buzz for thousands of gypsy hippies who followed the band across the country with Deadhead-like zeal. So you can imagine the "phan" reaction when Live Nation let it slip in January that the onetime college act would be reuniting for a summer tour. The concert promoter's website nearly crashed on Mar. 2 when tickets went on sale.