Why PhDs voted overwhelmingly for Barak Obama in this election cycle?

One explanation would be that so far the scientific community took the biggest employment hit during this recession, therefore people voted with their wallets. For example, Monster Employment Index for the San Francisco Bay Area shows that over the last 12 months job demand in Life, Physical, and Social Sciences category fell 50% ( Oct, 07 - 121; Oct, 08 - 61).
http://corporate.monster.com/Press_Room/MEI/Oct08/DMA/MonsterLEI_SF_Oct08.pdf

Military and Maintenance/Repair jobs were among the least affected.