I am pleased to be able to report that I get to take it after all!
It's only for a year, rather than two, so that I can hold on to my current job and have an actual position to go back to at the end of the term. This is actually not a bad thing, as it is going to be a big change for me, so a year is a good length of time to figure out if I like it or not! If I do like it (and they like me), there is a possibility that they'll be able to find a permanent position for me, although no guarantees.
It is a promotion. This is always nice.
It is a chance to try something different, and to challenge myself with increased responsibility.
It is a change of scenery. This is also nice.
All in all, this is very good news. Although the paperwork isn't completely done yet, so I suppose the carpet could still be yanked out from under me. Let's hope that doesn't happen!! *frantically begins knocking the wooden desk*