The couple began swaying to Billy Joel's "Just the Way You Are" – until the DJ abruptly cut to Michael Jackson's "Wanna Be Starting Something."
By then, guests already knew what that "something" was: a baby!
"Because of you, I'm pregnant!" the Today coanchor had revealed earlier in her (nonalcoholic) toast to Feldman, 45, the Washington, D.C., communications strategist she dated for four years before their engagement last May.
About 80 family members and friends jumped up and cheered.
"I'm pregnant with hope," an emotional Guthrie added, "full up with gratitude. I'm bursting out with joy."