Some of this year's obvious exclusions are Ang Lee's Lust Caution, which was denied submission by Taiwan because the film is hardly representative of the country's film industry, and Julian Schnabel's The Diving Bell and the Butterfly, which was passed over by its potential submitter, France, in favor of Persepolis (as was La Vie en Rose), which could have settled just fine with being an Animated Feature nominee. Other disappointments include The Band Visit, which was denied for having too much English dialogue, and The Kite Runner, which can't be submitted by Afghanistan because it was directed by Marc Forster, a Swiss-American, and featured an international crew. Afghanistan ended up with no submission, while Israel had to quickly substitute The Band Visit with Beaufort and Taiwan had to replace Lust Caution with Island Etude.
Last year, the Academy retooled some of the restrictions for its foreign-language category, although now it appears they could use some more tweaking. Also, I would like them to retroactively honor excluded films of the past, which they could do in some way without revoking the Oscars it has handed out (except the one for Tsotsi -- that one was really undeserved, and I'll say it again and again).
The record 63 films eligible for the foreign-language Oscar were announced last month by the Academy, and Cinematical's Eric D. Snider comments on that list here.