Yep. Here's the money stuff, with detailed frame-by-frame analysis at the link:
"Neither John nor Jackie Kennedy are smoking a cigarette. The smoke has been caused by some explosive reaction, such as the detonation of a firearm cartridge. Such smoke remains where the gun is; it does not travel with the bullet. The fact that this smoke appears in the sequence at the same time as the fatal injury, and that it emanates from the left-hand-side of JFK's head, where Jackie Kennedy has positioned herself, means that President Kennedy was killed by his wife.
I am not the first to reach this conclusion. This view is shared by someone calling themselves 'Nohup' who, in a public forum on 3rd April 2008, wrote "After studying the Zapruder film for nearly 20 years, I've come to the conclusion that the only person verified to have the access and angle to have delivered the fatal gunshot to JFK was Jackie Kennedy. The telltale sign is right before his head explodes, where she moves forward with something in her hand."