David himself made the following mention of the project on his own website here...
"David & Orb Rumours True – Up To A Point - Recent comments by ambient exponents The Orb's Alex Paterson that they have been collaborating with David Gilmour are true – up to a point. David has done some recording with The Orb and producer Youth, inspired initially by the plight of Gary McKinnon (see our related stories). However, nothing is finalised, and nothing has been confirmed with regards to any structure for the recordings or firm details re: any release plans"
Add to this is the following snippet of footage posted on YouTube featuring Dave jamming with Youth! Watch the clip here which makes mention of the release in October of an album called Metallic Spheres!
(with thanks to Nick King on the orbxmission mailing list for the pointer)