Will Roberts vote for marriage?

The New Republic thinks he might.

After all, Roberts has seen what a watershed decision Windsor has been, and he must surely recognize that if the Windsor majority takes the final step to recognize full marriage equality (as it should), that decision will be even more historic and undoubtedly one of the greatest legacies of the Roberts Court. Will Chief Justice Roberts be content to have such a momentous ruling be issued over his dissent, or will John Roberts want to be part of one of the greatest legacies of the Roberts Court?

We should know by the end of June.

That would be a 6-3, far more satisfying that a 5-4.  Most commenters think that Alito will go with Thomas and Scalia in opposing equality.