Other than Fruit Rollups, Exchange rollups are my second favorite type of rollup.
This is no exception as Exchange Server 2007 RTM Rollup 7 and Exchange Server 2007 SP1 Rollup 3 have been released. These updates contain a long list of updates and security fixes. The security bulletin 08-039, posted yesterday not only effects Exchange Server 2007, it also effects Exchange Server 2003. The rollups are recommended updates for everyone, however if you have and QFE fixes installed you will want to verify if this rollup supercedes that QFE, or if you will require a new or need to reapply your QFE after installing the rollup.
You can find the full description of Update Rollup 7 for Exchange Server 2007 RTM here. Download the update here. - You can find the full description of Update Rollup 3 for Exchange Server 2007 SP1 here. Download the update here.
You can also download just the security update for Exchange Server 2003 SP2 here.