With the release of the Critcal Patch Update for January 1020 Oracle has made E-Business Suite 11i patches cumulative. While Release 12 customers have had this capability, this is a welcome relief for 11i customers, making it much easier for them to stay patched current.
The prerequisites are minimal. You need to be at least at version 11.5.10 CU2 ATG RUP 6, but this is no more strict a requirement than previous (non-cumulative) CPU's.
There are also potentially a few prerequisite and post installation patches depending on the products you have enabled but these are also limited in number.
Overall, we are very pleased with this announcement. The only folks this is not sure to please are those that were using this as their last lame excuse for not applying E-Business Suite CPUs.