A friend passes on this item from The Hill:

Sen. Joe Lieberman (I-Conn.), the Democratic Party’s 2000 vice presidential nominee, is leaving open the possibility of giving a keynote address on behalf of Sen. John McCain (Ariz.) at the Republican National Convention in September.
Republicans close to the McCain campaign say Lieberman’s appearance at the convention, possibly before a national primetime audience, could help make the case that the presumptive GOP nominee has a record of crossing the aisle. That could appeal to much-needed independent voters.
McCain has yet to ask Lieberman to speak, either in primetime or elsewhere, at the convention. But if McCain thinks it will help make his case for the White House, as some of his allies suspect, Lieberman would be willing to speak on his behalf.
“If Sen. McCain, who I support so strongly, asked me to do it, if he thinks it will help him, I will,” Lieberman said in a brief interview.

This isn’t quite stunning, as Lieberman has been on the campaign trail with McCain quite a bit. And we had sitting Democratic senator Zell Miller giving a fired-up speech at the 2004 convention. But Miller was a hawkish, socially conservative Democrat whose party had left him. Lieberman speaking to the Republicans — besides driving the netroots to new heights of spasms of incoherent rage — would be a pretty compelling testament that “one candidate claims that he will reach across the aisle, but has rarely done it in his brief career; the other candidate has actually done that through much of his career.”