It’s not new: Debian is virtually nonexistent in Ubuntu’s communication. It seems that the last Ubuntu release to acknowledge its Debian origins was Dapper (June 2006), maybe because that was the “Long Term Support” release.
The fact that there’s no “Ubuntu is based on Debian” paragraph on www.ubuntu.com was raised during Debconf, and it was supposed to get fixed, but it seems that it didn’t happen for some reason (there was such a paragraph before the website redesign).
In other news, I’ve been trying to install Ubuntu Gutsy inside qemu, but it fails miserably while booting the installer. I removed the “quiet” and “splash” options from the kernel cmdline, and discovered that after trying to “mount the root filesystem”, I get dropped into busybox with no error message to google for. Feisty fails as well, but Dapper boots fine. So much for the Ubuntu is an ancient African word, meaning “I can’t install Debian” joke!