On immediate consideration, the answer would seem to be - nothing much.
But the Conservative spin machine sees a similarity, I guess, which explains why TWO of us at the Star have received messages from the party's HQ in the last 24 hours - asking us if we're going to write or comment on Dion's weatherman stint the same way we did about Harper throwing the football with Peter MacKay after Belinda Stronach's dramatic floor-crossing in May, 2005.
I apparently was on TV afterward in 2005, saying the Harper-MacKay stunt made me cringe (still does, actually). So Conservatives wanted to know if Dion doing the weather made me cringe too. Another of us had called the football game a PR display, so the Conservatives wanted to know if that's how he'd write about Dion doing the weather.
I'm assuming that if two of us got these messages at the Star, there are other reporters out there getting them too. In other words, they're now digging through their three-year-old records, looking for stuff said about Harper while he was in opposition - stuff that made them mad, apparently - and trying to leverage that into negative coverage of Dion.
I don't recall any political party doing this in the past - despite some Conservatives' conviction that the Liberals dictated negative media coverage of Harper, then and now. For the record, when Liberals did try to get me to write that Harper had a "secret agenda" or that he was scary in opposition, I'd usually tell them "you would say that, wouldn't you?" and tell them it was hardly front-page news that Liberals didn't like Harper. Same thing applies to Conservatives.