I'd count Star Trek. - Edit 2
Before modification by Craig at 31/08/2009 07:57:04 PM
...Watchmen and Star Trek stood out for me, by far.
Watchmen was back in March, so that definitely doesn't count. But <I>Star Trek was the first weekend of May, which (at least for us in the movie theater biz) is traditionally the "opening weekend of the summer."