It is possible to have a Gmail account and add POP3 accounts to it.
create a Gmail account using regular old Gmail
create your email accounts in DreamHost
in Gmail to to Settings>Accounts
Look at the section "Check mail from other accounts (using POP3)"
It is not perfect, but it works
Also, if you already have an existing free Google Apps account from a different domain, you can add other domains to it and create a limited amount of email accounts for that domain (while still keeping your account free)