A grep of 0.2808 doesn't show the error message you're getting. I think you either don't have 0.2808 or don't have it in the path for the Perl you're running CPAN on.
Comment on Re^3: What to tell Module::Build, and where?
~$ perl -MCPAN -eshell
cpan shell -- CPAN exploration and modules installation (v1.7602)
ReadLine support enabled
cpan> install Module::Build
CPAN: Storable loaded ok
Going to read /home/kai/.cpan/Metadata
Database was generated on Sun, 20 Apr 2008 05:29:45 GMT
Module::Build is up to date.