Heh, and now you see how we all became obsessives about smoking meats, Jerz. Well, 225-250 is a solid temp depending on what prep you're going for ...
A fatty can be as simple as taking roll of breakfast sausage, slathering it in some sauce or a spice rub, and throwing it in the smoker ... that's the low end of things and is delicious as a biscuit sammich in the morning. But if you want to experiment a bit, you can stuff sausage with cheese, veggies, bacon, etc. and roll it and then wrap it in bacon; I'm partial to a Bacon Explosion myself and if you want to see the step by step click here:
http://smokinitforums.com/index.php?topic=90.0Fatties are quite easy for the novice smoker and can really let you stretch your creative wings. For example, a leaner sausage like venison really benefits from par cooked bacon in the interior wrapped in a bacon weave. Bulk Italian sausage prepared this way is amazing as well ... think of the fatty as a sausage meatloaf.
On the temp issue, my best advice is that if you're doing just a plain sausage "football" then hit it at 235-250 and you'll see some decent fat rendered. If you've got bacon inside and out, go 225 because the bacon fat will render and self-baste the sausage ... it'll need some time to get happy.
These things smoke very quickly and I typically shoot for an internal temp of 160-165 and then 5-7 minutes under the broiler after a coating of BBQ sauce to caramelize it and crisp up the bacon.
