The Stockholm International Film Festival always has some big guests involved, previously luminary filmmakers such as Dennis Hopper, Lauren Bacall, Gena Rowlands, Ang Lee, David Cronenberg, Roman Polanski, and Terry Gilliam have all taken the time to be involved in the festival.
Currently submissions are still open until 12th of September. Reading the guidelines, it is important that if you are submitting your short film it is either on 35mm print if you plan on entering the 'in competition' section or BETA (SP) to have your film screened Online. The submission page can be located here. The 'in competition' section means that before each feature plays, a short film will screen, and I think there is nothing more exciting then being a support act for a feature film. Remember to read what documentation you will need to supply if your film is selected as there is quite a bit.
For filmmakers, the festival provides many networking soirées where cocktails are provided, so with a Swedish Blue, Glogg or Polar Bear in your hand, or even all three, you will be able to liaison with other filmmakers and industry professionals (Just don't let that script fall out of back pocket having eighty or so pages spilling everywhere giving up the game that you had plans to pitch your ideas for funding). Just remember not to get too drunk otherwise you'll end up like Terry Gilliam and his Producer as having signed to make Brazil and not quite remembering what happened or who was signing for what, and why.