This script builds dovecot with support for SSL. As such, you must have
openssl installed - openssl-solibs is not enough in itself to meet this
requirement.  Additionally, dovecot will be compiled with POP3 support.
Unfortunately, dovecot does not have a man page at this time, so you'll
have to find your documentation elsewhere.  A few examples are included
in /usr/doc/dovecot-$VERSION. The dovecot team operates a wiki that may 
prove useful:  http://wiki.dovecot.org

You should create a dovecot user to run the login processes on your server. 

From the dovecot-new release posting comes this word of advice:

  Remember to read http://wiki2.dovecot.org/Upgrading/2.0 before
  upgrading from v1.x. Although there is automatic config conversion,
  it can't handle everything, so reserve some extra time for upgrading.