The Riverton Apartments in CD 2007-CD4 was one of the first headline defaults in CMBS due to overly optimistic proformas and more importantly, a rent-control flip plan by some private equity group. These will continue hitting the news wires and be a main focal point for CMBS defaults for news outlets over the next 6 or so months - just wait.
The Appraisal came in much lower than expected, though, according to a Citi report out last week (sorry no link). Appraised at $340mm in Jan 2007, by some guy who hopefully has since lost his job, the June 2009 appraisal came in at just $108mm - still just a 4% or 5% cap rate. Interest shortfalls are eating into the O class.