found #491590 0.6.1-1 thankyou http://buildd.debian.org/fetch.cgi?&pkg=cegui-mk2&ver=0.6.1-1&arch=amd64&stamp=1224450974&file=log - if you check the build log, SILLY is not compiled into the cegui package. The SILLY library isn't even packaged for Debian!!
Here's the lines from the log: checking for SILLY... no configure: Image loading via SILLY by OpenGL renderer disabled -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]