In the past, perhaps, that different states had different educational goals militated against any kind of joint response to students' educational needs. Now, with common standards in place, states could more powerfully pool their talent and resources to enhance their response. The only areas this has been happening so far have been in the writing of the standards themselves and in the development of new tests--both of which were "easy" for the states because these efforts were paid for and orchestrated by someone other than the state departments of education. Now we need this kind of sharing in areas like professional development for teachers and principals, curriculum materials selection, public information, and so on... but nary a joint initiative in sight. Instead, leaders seem foggy about the impending changes or dedicated to business as usual.
If you are interested in this topic, here is the powerpoint: