Former Led Zeppelin lead singer Robert Plant will perform as a special guest on at least a handful of shows on the Who's upcoming U.S. tour. Plant is confirmed to appear July 29 in Hershey, Pa., July

Former Led Zeppelin lead singer Robert Plant will perform as a special guest on at least a handful of shows on the Who's upcoming U.S. tour. Plant is confirmed to appear July 29 in Hershey, Pa., July 31-Aug. 1 in New York, Aug. 24 in Tinley Park, Ill., and Aug. 25 in Indianapolis. The New York stand at Madison Square Garden is rumored to be expanding from two shows (already on sale) to four.

As previously reported, the Who tour kicks off June 28 at the 1,400-capacity Joint at the Hard Rock Hotel in Las Vegas and will close Aug. 31 in Wantagh, N.Y. At deadline, it was not known if Plant plans to be present on all dates of the Who's trek.

Meanwhile, Plant has also been added to the July 20 lineup of the annual RockFest weekend. Slated for July 18-21 in Cadott, Wis., the event will also feature Journey, Ted Nugent, George Thorogood & the Destroyers, the Scorpions, Meat Loaf, Cinderella, Poison, and Loverboy, among others. For more information, visit the festival's official Web site.

The Who drafted Plant to perform last month during a week of London benefit shows for the Teenage Cancer Trust. Plant and his band Strange Sensations appeared Feb. 9 at Royal Albert Hall on a bill with Paul Weller, and his former Zeppelin and Page/Plant bandmate Jimmy Page, who performed with Gary Moore.

Last summer, Plant toured the U.S. briefly with Strange Sensations. At the time, he revealed to Billboard.com that the band was planning to record a new album for a 2002 release. "Obviously, these are different days. This is not 'Physical Graffiti' that's coming up," he said, referring to Zeppelin's 1975 Swan Song/Atlantic masterpiece. "But that's OK. I understand exactly where things are, and I don't have any illusions or delusions. But what I want to do is make this thing really strong, and in doing so, be realistic about what we're doing here."