From the New York Times' writeup of their joint appearance in Indiana today:

Mr. Bayh made the only introductory speech at the event at Concord High School here, referring to Mr. Obama as "my friend, our neighbor" and noting that this was Mr. Obama's 42nd visit to the state.

Mr. Bayh, however, focused his remarks on the political battle that lay ahead and marveled at the effort Mr. Obama is making to win the state, calling it "a very unusual thing."

When Mr. Obama took the stage, the two men embraced, Mr. Obama smiling broadly as he patted Mr. Bayh on the shoulder. And during the question-and-answer session that followed his remarks on energy policy, Mr. Obama went out of his way to praise Mr. Bayh.

Otherwise, that was it. Nothing about an announcement. In fact, according to the WSJ, an Obama official all but confirmed that the candidate won't announce his running mate until after he returns from vacation on Aug. 16.

More veep buzz in the VP Watch blog.