Someone on FB posted that they got rid of the ellipses (...) in 1 Sam 13:1, which was a holdover from the RSV.
That's probably the first place that I would have looked to see if it had been changed. There have been previous threads about this verse and the ESV's translation of it, etc.
Here is the before and after:
2001/2007 "Saul was … years old when he began to reign, and he reigned … and two years over Israel."
2011 "Saul lived for one year and then became king, and when he had reigned for two years over Israel."
---------- Post added at 01:25 PM ---------- Previous post was at 01:17 PM ----------
When the ESV Study Bible goes through its next printing, I'm assuming that it will have this updated text. What about the MacArthur Study Bible, other Study Bibles and other resources that use the ESV like the concordance? How long will it be before they will have the 2011 text? Well, those that use the KJV (especially) as well as older modern versions that aren't being updated every 4-6 years don't have that problem.

Some will say it's not a big deal, and you may be right. But others will just have to have it and will buy a new copy every time an update is issued, however minor.
I think it was a good while before ESV text and reference versions became available with the 2007 text as the older edition had to sell out first, presumably. The person who posted about the change to 1 Sam 13:1 on FB said he had the New Classic Reference Bible with the 2011 text. I saw a hardcover copy of it shrinkwrapped in a store a couple of months ago. I didn't know it was a 2011 text edition, partly because I wasn't aware of a 2011 text edition at the time. The construction looks to be of better quality. The copy I saw had a sewn binding whereas my original in 2002 was glued and started coming apart within a couple of years.