d-i in c't
I'm following this at one remove through a German language barrier, but I understand that the big and important German computer magazine c't has released an issue containing a Debian sarge CD with d-i. I've had a chance to read a machine tranlated version of the accompnying article, and look at the CD. Aba has some more first-hand information
The CD uses d-i preseeding to automate installs. Looks to me like you have to boot it with "auto" to get that, the default is a normal install. Good decision. Other mods include their own partman recipe for server partitioning, their own kernel (including kernel udebs!), and a "ctsrvcfg" that configures packages specially. So it's really on the verge between being Debian and a custom sub-distribution.
Kinda neat that rolling such a thing is (relatively) easy enough to do that a magazine has the resources to do it; though on the other hand I'd be happy to have stock d-i media on there too. It will be interesting to see if we hear from many new users because of this.