Pete Hines confirms on Twitter...

http://twitter.com/dcdeacon

http://uk.ign.com/articles/2012/07/26/bethesda-exec-we-have-not-announced-dawnguard-for-any-other-platform

http://www.vg247.com/2012/07/27/dawnguard-not-announced-for-pc-playstation-3/

http://www.gamesas.com/topic/1399019-pcps3-release-date-thread-part-10/