Here’s the link to the Apple Support document describing the update and how to get it.
10.6.5 promises increased performance in playing well with Microsoft Exchange, better image processing with iPhoto and Aperture, adds SSL support for transferring files with iDisk, resolves an issue syncing Address Book with Google, allows systems with a Mac Pro RAID Card (Early 2009) to be put to sleep, and adds RAW image compatibility for additional digital cameras — among other things.
See the full support document for details.
