Daniel Erickson has posted a brief not on the Star Wars: The Old Republic site that explains to players the necessity behind leaving ranked warzones out of the v1.2 patch deployed last night.
After careful consideration, it is clear that to make Ranked Warzones the feature we all want it to be is going to take a bit more time. I apologize for any disappointment this may cause and ask for your patience as we work to make sure the Ranked Warzone Preseason launch is polished and fun.
According to Erickson's post, ranked warzones will be rolled out in stages.
Read the entire note on the Star Wars: The Old Republic site.