it is true that kerry picked edwards as his VP on july 6th, but the democratic national convention that year started on july 26th. this year, the convention is a whole month later, starting on august 25th. if obama sticks to the kerry schedule of announcing his pick 20 days or so before the convention, the announcement will come next week. (but there's no reason to believe he will stick to that schedule)
the reason why this year's convention is so much later is because of the olympic games in beijing. usually the first party convention is held at the end of july and the second shortly thereafter. by tradition, the party who doesn't have the white house goes first. but if they followed the traditional calendar that would put the republican convention competing for media attention with the opening ceremonies. the republicans are well aware which media spectacle would win out in the war for ratings. so they wanted to schedule their convention after the games were over. the democrats didn't want to cede the month of august as republican convention anticipation month, so they moved their convention back until after the games too, leaving a week or so after the games end for the excitement (and headlines) to die down. that puts the democrats at the end of august and the republicans at the beginning of september and leaves a short two months for the post-convention election season.
the only thing i don't understand is why the olympic games only mucked up things this year. the summer olympics are every four years, putting them on exactly the same schedule as the american presidential election. you'd think the same logic that pushed both conventions way back this year would have applied every other presidential election year.
