Greece Reporter says (in rather fractured English), that Messinia in the south-west Peloponnese "has become a film set" for Linklater for what is apparently the third part of the trilogy. Meanwhile, Flix adds to the intrigue, reporting that Linklater's Detour Films is co-producing the picture with Christos Konstantakopoulos’ Faliro House, hence the setting. But that's not the only connection as Faliro House was also behind the film "Attenberg," which was directed by Athina Rachel Tsangari, who had a small role in Linklater's breakout "Slacker." Coincidence? Moreover, the The Sceptical Traveler blog confirms that Hawke is staying on the island, and adds the (rumored) title is "Before Midnight." Whatever it is Hawke is working on, production apparently started on August 15th and will continue until September.
So put that all together and what do you get? Well, mostly just evidence that Hawke is in Greece working on something. Curiously, Delpy is absent from all of these sightings, which raises a flag. However, with Hawke previously teasing that "The biggest change between this one and the last one is the Internet," could Jesse now be living abroad and catching up with Celine via email or Skype? Is he working on something else entirely? Who knows. But hopefully, some more official word on just what Hawke is doing in Greece will emerge soon.