Just unwrapped and tested an extra (read late) Christmas present, a Lowepro Fastpack 350. Looking good so far. It is big, but I'm a big guy, so I consider it a good thing if it is comfortable, and it is. Has a pretty good harness system considering the price, with waist belt, and pretty good shoulder padding.
The main feature is easy access to the camera via a side opening. I'm able to open it, it and grab the camera directly with my left arm. You don't have to take it off either, to put it back again. Just slide the right arm out of the harness, and slide the whole pack to your front (almost like a sling style bag).
The direct access camera compartment has plenty of room for my entusast K20D with grip and a 300/4 with reverced hood. I'm pretty sure it can take most pro sized DSRL bodies with a 70-200/2,8. There is also plenty of room for my 16-50/2,8, 50-135/2,8, my 540 flash, and a couple of medium sized primes. When used as intended, you have to take the pack of your back to get access to the rest of the equipment, but with a bit creative use of the velcro dividors, I can use the side opening to get access to most of the lenses.
There is also plenty of small pockets, intended for extra battery, cards filters etc.
Above the main compartment, there is a general store compartment for whatever you need to carry on a day hike. Not enough room for cooking facilities, but plenty of room for some extra clothes and food.
A nice padded laptop compartment is another nice feature, with maximum protection, because the compartment is near to your back.Off cource ther is law against using this for other stuff like a book or two, or more clothing.
It is also possible to mount extra accessories, like lens cases, water bottle case etc at the harness system. The one thing I'm not entusistic about isthat there is no obvious place to carry a tripod. But I think I can work out a solution, using some extra straps. Need to experiment a bit further with this.