Important...but not life-altering...
The powers that be have made a few minor changes to the OWL's this term. The OWL thread is here. Read the whole thread before term starts to get a good foundation for your OWL!
Notable changes include a few additions to your OWL options, but the most important change is swatching. What's a swatch? It's a small piece of cloth knit or crochet in the pattern stitch, which you will then wash & treat as you would the finished garment. You will then see if the end result is what you're hoping the final project to look like. If not, swatch again with different needles and/or yarn.
So, say you're making a sweater or socks. You are permitted to knit only 2-3 inches (that's 5-7cm for you metric folks) of a sleeve or sock top as your swatch.
In addition, if you are going to propose an OWL, you must submit as many swatches as you will have different yarn/needle combos, up to 5 swatches. So if you're making a small herd of baby hats in various weights and needle sizes, you need to swatch 5 times. If you're making four pair of socks out of the same yarn, on the same needles, in the same pattern, you only need to make one swatch.
Please do not forget the importance of swatching! The OWL examiners want you to not only finish the project, but have the end result that you are hoping to achieve, and a swatch puts you a heck of a lot closer to that goal.