Ben,I think this is corn speedwell. It is best controlled with preEmergents in the fall. Corn speedwell does have a rather inconspicious blue bloom that on closer inspection should confirm our mystery weed ID. There are other similar speedwell varieties but this one is a very common spring weed in lawns. http://msuturfweeds.net/details/_/corn_speedwell_39/
Jon at this point with rising temps I would not be too concerned with winter annuals. Hopefully you’ve already applied preemergents this spring for summer annual weed control. If not, you’ve got a long row to hoe! The original date of this post was 04/7/2012. Did you make that inquiry? If not, what kind of grass are you growing and what/when did you last apply control products?