Bush was talking to Prime Minister Tony Blair at the G8 summit in St. Petersburg and said the following: (during lunch, while chewing, apparently - I haven't seen the video)
The two leaders also referred to an offer by Blair to help. Blair said Rice has "got to succeed" if she goes out to the region.
Bush replied: "What they need to do it to get Syria to get Hezbollah to stop doing this sh*t." Shortly afterwards Blair noticed the microphone and hastily switched it off, but not before the recording had reached news media.
Maybe it was just slip...or a warning to Syria.