tilecache: metatile - no module named image

if you get "No module named Image..."

you need the python imaging library

wget http://effbot.org/downloads/Imaging-1.1.6.tar.gz
python setup.py install

now gets "cannot read interlaced PNG files"

add this in your map file:
OUTPUTFORMAT
      NAME "png"
      MIMETYPE "image/png"
      DRIVER "GD/PNG"
      EXTENSION "png"
      TRANSPARENT FALSE
      FORMATOPTION "INTERLACE=OFF"
END

my tilecache.cfg contains this:
[base]
type=WMS
url=http://x.x.x.x/cgi-bin/mapserv?map=/../my.map
metaTile=true
metaSize=1,1
extent_type=loose
extension=png