The following link is for a discussion (with a table of when transitions would occur for DMA's) of Dish Network switching their equipment from Analog to Digital to receive Locals.
In the first message, there is a link to a file which actually gives dates of when Dish would update the equipment to receive the Digital SD Locals that would then be transmitted (rather than the analog that is currently being retransmitted). For instance, the transition for Kalamazoo/Battle Creek/Grand Rapids, MI is slated for July 21, 2008.
OP was asking about DMA 144 (which on this list is listed as Palm Springs, CA) is scheduled for January 19, 2009.
Geoff