quilt is kind of nice, I think. It might be that there actually is a way to sanely maintain a huge set of patches as patches, provided that you put some effort to it.
The geek in me found a new toy and couldn’t stop playing with for a while. So as a result the maemo gtk+ patch is now available also in smaller pieces in the svn repository. Sadly the treeview is still quite a big ball of spaghetti.