I must apologise for misleading people about the closure of the Athens airport metro link over the summer. A wiser head than mine - DeTraci Regula of the About site on Greece, http://gogreece.about.com/ - now tells me that, to quote:
"Several STATIONS will be closed - ie, the train won't stop there. but the LINE will continue to operate all the way from the airport to the city center and vice versa. I read the initial articles on this very carefully and then contacted the operators directly because it did sound as if it could be taken to mean a complete closure,and that didn't feel right to me.
Now, in reality, I would not be surprised at all if there are indeed occasional full closures during this period - but it will not be closed for the entire period. Also, they will be providing some sort of bus service to the open stations during the station closures."
Apologies again for the initial misleading info.