If after the 30 day Microsoft exclusivity deal, you were waiting for the PC or PS3 version to be released, you were to be very dissapointed but have no fear there will be some info about it some time this week
http://www.pcgamer.com/2012/07/30/dawnguard-pc-info-coming-later-this-week/?ns_campaign=article-feed&ns_mchannel=ref&ns_source=steam&ns_linkname=0&ns_fee=0