Now that's what we're talking about: Summerfest has announced Bob Dylan and Willie Nelson as the latest Marcus Amphitheater headliners; the two will split a July 1 bill that, with any luck, will find time for plenty of duets and collaborations. Tickets go on sale Saturday, May 2 at 10 a.m., priced at $59.50 (Red), $49.50 (Yellow) and $37.00 (bench), with a limited number of free lawn seats available the day of the show, Summerfest promised via Twitter.