Duffy / Photo by Karen Chan

1. "Wow, what's with all those people onstage?" my companion asked as we stopped by the MySpace stage where a dirtbag choir was working hard (and in unison) to keep the butt-rock flame alive. With five musicians and 22 singers -- many of them pickups from local Chicago bands -- Boston's Bang Camaro come on like Kiss meets the Polyphonic Spree, proffering punchy anthems with memorable choruses about leather and lightning that might as well be the soundtrack to your next 7 Eleven parking-lot hang. A perfectly pleasant way to start a very hot day of music.

2. Introducing "Warwick Avenue" as a song that hasn't yet made it over here (meaning the U.S. or downtown Chicago?), current SPIN cover girl Duffy offered the afternoon's first head-scratcher. That it's on the domestic release of her debut album Rockferry (more than a half-million sold) didn't seem to matter. Her vocals were typically gorgeous, and in her high heels and cute sailor-inspired dress, she was playful and chatty between songs. Yet there's something perverse about hearing such stirring, intimate stuff in the sunshiney swelter of nearly oppressive 90-degree heat. When she offered to lighten the mood by performing the loping, barely midtempo "Serious," this audience member was begging for "Mercy," which, when it arrived at the end of the set, was sweet relief indeed.

More after the jump.