Bring it on!!!!!!!
Just dress for the weather. I normally wear a set of nato issue sleeka jkt/trs combo,available from army surplus,warm socks,insulated boots/thermal footbeds, hat/gloves. Toasti warm.Stayed out for 8hrs a couple of weeks ago at -5 oc,whilst sitting down.
A must have is a good thermos, insulated mug, and a wide mouth food flask. You cannot believe the difference this makes. Soups/stews are ideal,but rice pudding/ apple crumble and custard can make you feel ever so smug and warm.
Also keep your gear warm, bubble wrap is good,especially around the battery area, as is thin karrimat, especially around long lenses.
heat packs can also be useful to extend battery life. I've used my gear at -10 to -20 oc with little problems.
Rob
www.flickr.com/photos/robaurdu/