You bet. OpenTable is capable of "listening to" the data sent to and from client POS machines. OpenTable listens for certain events, such as "New Table", "Entree Ordered", or "Desert Ordered". These events give OpenTable cues as to how far along that table's service is at any given time. (If a check was recently dropped, for example, OpenTable would know the table should be turned soon.)
Although OpenTable can listen for somewhere around 8-12 different types of events (don't quote me on the numbers - I'm not sure about that), Aloha only generates three: New Table, Entree Ordered, and Desert Ordered. There are several other types of events that I wished Aloha generated, such as "Check Dropped" or "Entree Plated"...
For the three events that Aloha generates, OpenTable picks them up perfectly and updates the table status appropriately. Open table even picks up the payee's name from a credit card (if one was used) and logs the amount the payee spent (for marketing purposes, if needed).
I hope this explaination helps. From what I hear, I think we are among the first restaurants to integrate the two. We will be training our staff in the integration in a couple weeks, and I might have more details to report after it goes into full use.