Many hints were spread throughout the internet. A couple of weeks ago David's wife Polly Samson tweeted about "Crosby and Nash in the studio singing like birds tonight", for example.
This time Graham Nash himself confirms the information in an interview he gave to Neil McCormick. He confirms that "he and David Crosby are singing with David Gilmour on his new record'. This remark can be found around 12'50 on THIS video.
Graham also confirmed that the album is being recorded at Brighton (David's house at Hove).
Moreover, a couple of months ago, Phil Taylor (David's guitar tech) confirmed to Effectrode that David was pleased with the Helios Fuzz pedal he bought from them and will be purchasing another one "before he starts recording".
For now there's no official info on the musician's website, as soon as we have any news Progshine will let you know.
This will be the first David Gilmour studio album since On An Island (2006).