The Elections Act does not permit results to be broadcast in any time zone before polls have closed. The reasoning is that Canadians should not be influenced by the results from a time zone whose polls have closed and where results can be gleaned.
Of course, that was a more enforceable matter when there was not an Internet; only Canadians who were phoning across the country could share results. But once the Internet surfaced, people could email and non-Canadian sites could publish results.
Efforts were made to suppress those results and crack down on bloggers and others who transmitted results. The biggest losers were the television networks, which had to run pre-game-type programming until local polls closed, then join the national broadcast in progress. In the west, it often meant joining a telecast with an overall outcome long since resolved.
On Friday it was made clear the law will change by the next federal election. Given that there are staggered polling hours that mitigate closing times, there shouldn't be much of an influence from east to west. And all of the technological workaround and crackdown will be a thing of the past.
An interesting touch: The federal minister who announced the change Tweeted out the announcement.