According to a blog post by Chris Kenyon on the Canonical Blog, the Ubuntu Server 11.10 release will be simultaneously available for x86, x86-64 and ARM-based architectures. The base image of the releases will be the same across architectures with a common kernel baseline. The ARM architecture will also be part of the long-term support (LTS) version of Ubuntu Server in 12.04 and other future releases.
The Ubuntu Server on ARM initiative is a multi-year initiative gathering broad participation. More project information can be found on the Ubuntu wiki
