Steve Langasek, Ubuntu release manager, has proposed on the Ubuntu-devel mailing list to drop the alternate CDs for Ubuntu 12.10 Quantal Quetzal.

According to Steve Langasek, Ubuntu 12.10 Quantal Quetzal will be getting support for LVM, cryptsetup and RAID to Ubiquity, however, there won't be any RAID support in Ubiquity for this Ubuntu release, but you'll be able to set up RAID post-install or by using the netboot or server CDs:

As part of ongoing efforts to reduce the number of images we ship for Ubuntu, and to make the desktop image more useful in a variety of scenarios, Dmitrijs Ledkovs has been hard at work in quantal adding support for LVM, cryptsetup, and RAID to ubiquity. [...] It [dropping the alternate CDs] lets us tighten our focus on making the desktop CD shine: fewer images to QA, fewer different paths to get right (like the CD apt upgrader case) means more time to focus on the things that matter.

More information on this can be found on the Ubuntu-devel mailing list.