The Metasploit Framework is a development platform for creating
security tools and exploits. The framework is used by network 
security professionals to perform penetration tests, system
administrators to verify patch installations, product vendors to
perform regression testing, and security researchers world-wide.
The framework is written in the Ruby programming language and
includes components written in C and assembler.

This is just a repackaged version of the tarball you get from the
Metasploit download page. To succesfully run the framework web 
interface, install the rubygems package (avalaible on SlackBuilds.org) 
and then get the Ruby On Rails gem via the commannd:

# gem install -v=1.2.2 rails

If you want to use the Autopwn feature of metasploit, install the
PostgreSQL database server (also avalaible on SlackBuilds.org) and
create a "metasploit3" database.
Finally, if you want to run the selfupdate feature, be sure you 
have subversion installed.