I had a little trouble installing and using drush on 1and1, and I wanted to post back the solution that worked for me. It's taken right from drush installation notes, but like all things opensource, it's good to spread the SEO to specifically 1&1 hosting which defaults php interpreter to php4. Drush needs php5.
Per the instructions, just force php5 by creating a .profile (you probably don't have one yet) in your home directory that contains:
alias drush='/usr/local/bin/php5 ~/drush/drush.php'
In this case, my drush is installed under /*/*/*/*/htdocs/[drush]
Just like the README.txt says, you'll need to log back in (via ssh) to reread .profile and let this alias become active.
Hope this helps!
-Bronius
