Not it doesnt need to be long. It can be done in short sleeve, but it needs to be a button up shirt.
Actually states that on the page:
Q: How long will it take me to learn to perform vanishes with the Raven?
A: It'll take you about an hour of practice before you're performing vanishes like a pro.
Q: Can I really perform it in short sleeves?
A: Yes, and your hands end up perfectly clean.
Q: Is any sleight-of-hand expertise required to perform the Raven?
A: No, the Raven does all the work.
Regaurding other effects:
Besides the vanish, you can even make the coin turn into another coin or shrink it into a miniature-size coin. Many additional effects are possible with bills, matchbooks, and playing cards.http://www.penguinmagic.com/product.php?ID=166http://www.penguinmagic.com/product.php?ID=245The power of Search
I spent most of my time going over the reviews of the Raven. I knew it vanished coins, though I wasn't sure if it could be done in a short sleeve or not. One of th reviews I read, left me with the impression I could only do it with long sleeves. It has great reviews and according to the sticky note, if you want to do some coin work, they recommend to get the Raven so that you understand how it works, though I may or may not use it all the time. I have better skills with card sleight of hand than coin sleight of hand, but I don't want to be one dimensional and only perform card effects. I wasn't paying attention to notice that it states on the page that the Raven could be used even with button up short sleeve shirts. I just wanted to check with some of the more experienced magicians to be sure it could be performed with short sleeve shirt.
What other effects besides vanishing coins, can you perform with the raven?