I had problems getting nested directories to be ignored; the top directory I wanted to ignore wouldn't show with 'svn status' but all the subdirs did. This is probably self-evident to everyone else, but I thought I'd share it:
EXAMPLE:
/trunk
/trunk/cache
/trunk/cache/subdir1
/trunk/cache/subdir2
cd /trunk
svn ps svn:ignore . /cache
cd /trunk/cache
svn ps svn:ignore . *
svn ci