Black Sabbath’s most recent release is the 1998 live album "Reunion" (Sony), which also contained two new studio tracks, including the radio hit "Psycho Man."

Prior to headlining this summer’s Ozzfest tour, Black Sabbath last performed together on Dec. 22, 1999 in Birmingham, England, for what it claimed would be the members' final show together. Similarly, following last year's Ozzfest, frontman Ozzy Osbourne [ tickets ] had announced that he would no longer perform on the annual festival; Osbourne has announced his retirement on several occasions, but has yet to honor such announcements.

In addition to his current touring plans with Sabbath, Osbourne is also working on his first solo album since 1995’s “Ozzmosis,” according to a VH1 interview with his wife and manager, Sharon Osbourne, held earlier this year.

Disturbed, meanwhile, continues to tour behind its March 2000, platinum-certified debut, “The Sickness” (Giant). The album features the hit single “Down with the Sickness,” which is currently at No. 16 on Billboard’s Mainstream Rock Tracks chart.

Originally slated to headline the second stage throughout this summer’s Ozzfest outing, Chicago-based Disturbed was moved to the mainstage lineup following the tour’s June 8 kick-off in Disturbed's hometown. On that date, thousands of fans filled the second-stage area during the group’s performance, causing a “near riot,” according to Ozzfest’s official website.

Disturbed is spending Ozzfest off-dates participating in the Big Day Off tour, a spin-off outing featuring fellow Ozzfest acts Papa Roach, Slipknot, Linkin Park and Mudvayne.

Ozzfest continues on Thursday night (7/5) in Dallas, and is scheduled to run until Aug. 12.