Couldn't find a topic about this after short looking, and this is perhaps old news, but I haven't seen anyone except me doing that jump in dustbowl. And I'm a regular on some 24/7 dustbowl servers, so I felt like posting a new topic here.
So. Ever annoyed of that damn engy nest inside the first cap of first level in dustbowl? The one just next to the frontdoor, up the small ramp, close to the windows.
Well, worry it no more! Just pick up a demoman, and stickyjump to
THIS spot.
Edit: Some more pictures to show better how to get up there.
A view of the first CP (with the jump target circled in white)
One way of jumping upStand hereAnd here we are. As stated on some of the replies, you will be an easy target, but this is where the "Teamplay" -part comes in. You have to rely on your team taking care of the other team while you take care of the SG. And if they can't, you can just try laying a stickyfield to the open area at right, and blow up everyone who walks there. For defensive use, it is fun until a sniper or a soldier notices you, and that won't be a long period of time.
As you can see from the first pic, it is reachable with a well placed rocketjump too (but a soldier is far more useless on offense there, because he can't lob grenades through the hole, like demomen can.) You can also escape to this spot from mad defenders, who are going on an "WE WON, NOW YOU AAR DEAD" -rampage.

.. its actually interesting how people actually do NOT expect you to be hiding in open, or behind them, when they go for the free points..
Happy jumping! (And hopefully just jumping, and not exploiting. Im gonna hate something if this is a bug.)