Spider-Man 3 is heading back for reshoots with the reasoning from Sam Raimi himself that there just wasn't enough action going on.

Apparently, according to IMDB, test screenings resulted in audiences saying there just wasn't enough action going on, and Raimi agreed. Therefore Tobey Maguire, Kirsten Dunst and James Franco are heading back in for some additional shooting. So is that there wasn't enough action, or there wasn't enough action with Goblin's son looking for revenge?

All the on set reports we've heard from people living nearby the filming has been about Thomas Haden Church and his Sandman character, there's not been much on the other two. Perhaps the audiences wanted some more continuity with the first villain?

Update: 29th August
According to Superhero Hype there may be reshoots but there have been no test screenings for the public.

So we're being told that the reshoots are all without a test screening? I doubt that. Okay, perhaps not full public, but I can imagine there were a good bunch of people sitting there to view it before they called people back for reshoots.