Canonical has announced plans to no longer support CD sized (~700MB) ISOs from Ubuntu 12.10. Kate Stewart announced in Ubuntu mailing list:
For the client, this release now has a consolidated Ubuntu image. There is no longer a traditional CD sized image, DVD or alternate image, but rather a single 800MB Ubuntu image that can be used from USB or DVD.
This means a single Ubuntu image will be available weighing around 800 mB in size. This image maybe burned to a DVD or written in a USB drive to install Ubuntu in your PC.
The step is taken mainly because of growing size of apps and kernel. Ubuntu had earlier announced plans to drop Ubuntu alternate CDs because RAID and encrypted installations are available in main image itself.











