Confusing directions: yes, teachers can prep, but subs see this all the time.
Reading this since I'll be a sub soon (if nothing better shows up): http://www.nytimes.com/2010/01/03/opinion/03bucior.html?pagewanted=1&th&emc=th
I think I posted about this before, but I'm too lazy to check right now. Doesn't hurt to read things again.
Subbing technically isn't that hard - except for the fact that you don't know the students very well yet, nor do you know the school very well yet, and that it's another person's classroom that you have no idea how to use yet.
It's like the first day of school for a brand new teacher every single day. Except I didn't do the prep for the whole school year.
I'm not particularly looking forward to subbing. But it's the best offer I have at the moment, and it'll have to do.