I’ve only just caught up with the Times’ David M Halbfinger and his magnum opus on Clinton/Streisand. One assumes he’s already shopping it as the defining book of the ‘08 campaign (The Making Of The Presidential Endorsement). A lot of it’s predictable – Barbra’s announcement went through more drafts than Yentl – but this stands out:

Still, the singer’s value to Mrs. Clinton shouldn’t be scoffed at, another Streisand associate said on Wednesday.
“We would’ve low-keyed it,” the associate said. “But the campaign says it’s a net plus. They polled it.”

Best not to take any chances.