This problem seems to be afflicting quite a few people, and 0.4.0 has added the gem installation, but many still have 0.2.x or lower installed.

If you've installed DBI from rubygems and get a LoadError or DBI::InterfaceError on use, referencing DBI::TypeUtil or "cannot load driver: YourDriver", make sure:

1) You have the appropriate dbd-* driver installed (dbd-mysql, f.e.)
2) You don't have an old, setup.rb installed version of DBI 0.2.x or lower.