Mozilla Corp. will unveil a release candidate of Firefox 2.0 later Tuesday, the next step toward finalizing the browser's first major upgrade in a year. According to notes posted in the developers' section of the Mozilla Web site, Firefox 2.0 RC1 is on track to debut Tuesday, Sept. 26. "This is just to let everyone know that the QA testing for RC1 is complete," read the note. Firefox 2.0 has already gone through a pair of beta versions; the last, Beta 2, was released at the end of August. Mozilla has not set a release date for the final. At...