When the Official Selection for this year's Cannes Film Festival was announced on Thursday, the film I was perhaps most surprised to see left out was Ari Folman's "The Congress." The film was ready in time for the festival, advance whisperings were positive, it has red carpet-friendly stars in Robin Wright and Jon Hamm -- and, of course, Folman's last film, the Oscar-nominated "Waltz With Bashir," was a hit in Competition five years ago. What gives?

Well, now we know: "The Congress" has been selected as the opening film for Directors' Fortnight, the independently programmed sidebar that runs parallel to the main festival on the other end of the Croisette.

That could mean that Cannes festival director Thierry Fremaux and his fellow selectors turned Folman's film down, and the Fortnight was the next best thing. Or it could be that grabbing the opening night of the increasingly prominent sidebar was a more temptingly prestigious offer than a standard slot in the Official Selection. Festival horse-trading is a complex business. 

What it doesn't mean, however, is that the film is sub-par or unworthy of a place in the bigger show. Just look at last year's Directors' Fortnight opener, also something of a surprise exclusion from the Official Selection: Pablo Larrain's brilliant political satire "No" emerged as one of the festival's breakout hits and landed up with an Oscar nomination. When it comes to generating festival buzz, being the big fish in the smaller pond can be a sound tactic.

Directors' Fortnight can be a happy hunting ground for critical hits away from the chaos of the main festival: in addition to "No," notable recent films to have premiered in the sidebar include Xavier Dolan's "I Killed My Mother," Ramin Bahrani's "Chop Shop," Bong Joon-ho's "The Host," Christophe Honore's "Dans Paris," Ray Lawrence's "Jindabyne," Francis Ford Coppola's "Tetro," Lynne Ramsay's "Morvern Callar," Stephen Daldry's "Billy Elliot," Bela Tarr's "Werckmeister Harmonies," Sofia Coppola's "The Virgin Suicides," Todd Solondz's "Happiness," Ang Lee's "Eat Drink Man Woman," the Dardenne Brothers' "La Promesse" ... even P.J. Hogan's "Muriel's Wedding." Ignore it at your peril, though I'm often surprised by the number of journalists who do just that.

Anyway, fingers crossed this bodes well for "The Congress," an adaptation of a short story by Stanislaw Lem ("Solaris"). Wright stars as an aging actress who agrees to an experimental procedure whereby her youthful form is scanned and replicated for future use and profit by the studios -- it's billed as a meditation on the future and the future of cinema. Part live-action and part animated using the distinctive rotoscope-esque style from "Waltz With Bashir," it should be an interesting match for Folman's sensibility -- the stills floating around the internet certainly intrigue. Jon Hamm, Paul Giamatti and Harvey Keitel also star.

Anyway, this news means six of the 10 films I was most hoping to see at the festival will definitely be there -- will any others pop up over the next few weeks? The full Directors' Fortnight lineup will be announced on Tuesday, with the Critics' Week picks also still to come.