Master warning symbol | DashboardSymbols.com
Edit: From the 2009 Owner's Manual:
Master warning light
When the ignition switch is in the ON position, the master warning light illuminates if any of the following are displayed on the vehicle information display:
. No key warning
. Low fuel warning
. Low washer fluid warning
. Parking brake release warning
. Door/rear hatch open warning
See “VEHICLE INFORMATION DISPLAY” later in this section.