Attention 2010 Worlds competitors:
According to the IBJJF website there are some strict rules regarding placement of gi patches.
Article 13 Rule 9 Shows this image with the proper placement for all your patches:
The Portuguese states "Above the knee", "Below the knee" -> "Leave a 15cm gap between the patch and the hem of the pants."
On the back of the pants the patch cannot be wider than 10cm. (Seems butt patches are out.)
Help a friend and pack a seam ripper. People were charging $10 to remove a patch in previous years.
Thank you to Mafu for bringing this to our attention.