Just got the PHD newsletter in my email and it seems they have adopted a new 10d fabric along with 900 (EU) FP down to make some pretty ridiculously light clothing. A full body suit including a hood and booties would weigh under 500g in fact.
Some more info here http://www.phdesigns.co.uk/waferdowngear.php and here http://www.outdoorsmagic.com/gear-news/phd-launching-new-ultra-light-down/10874.html
Strange though, they haven't posted temperature ratings for this stuff, like they do with all their other clothing and bags. My question would be how useful this gear actually is. Sure it's lighter than a fleece but it can't replace your 150g+ fill jacket. I suppose if you were hiking in mild climates (like 10C+) you could take these as your primary warm at half the weight of even PHD's own ultra pullover, but without temperature specs it's hard to know what they compare to.

