There was good news this week for travellers hoping to visit both Greece and Croatia's Adriatic Coast. Croatia Airlines announced that in summer 2011 their flights from Zagreb to Athens will include a stopover in Dubrovnik, allowing a direct connection between southern Croatia and the Greek capital. The flights will operate three times weekly (Tuesday, Thursday, Sunday) starting on May 31.
In test bookings on the Croatian Airlines website, the cheapest return ticket (Dubrovnik-Athens-Dubrovnik) I could find for June 2011 was 2071 kuna, approximately 282 euro. The cheapest one-way ticket from Dubrovnik to Athens was slightly more expensive.
Travellers hoping to make the journey in low season, or unable to adapt their itineraries to fit the days of the week on which these flights operate, will have to continue to choose among the other options outlined on my page about travelling from Croatia to Greece.
Croatia Airlines also announced another summer-only service likely to be of great interest to tourists travelling around southern Europe: a direct flight from Dubrovnik to Venice. The service will operate twice weekly (Thursday and Saturday) starting on June 16. At the time of writing it does not yet appear to be possible to book this flight online.