I just came back from a really good summer school on algebraic stacks, and the good thing is that there are some excellent notes to be shared. Jarod Alper wrote his own notes for his lectures, and these are a brilliant introduction to Artin approximation and Artin algebraization leading to a description of the local structure of algebraic stacks. For the other lectures participants are TeX'ing up their notes, so far Vistoli's lectures on gerbes (done by David Holmes) are available, stay tuned for the others as all of the lecture series were really good and worth a read if you are interested in algebraic stacks.