Apple has posted a combo updater for Mac OS X 10.6.4, for those users who want to update from earlier version (Mac OS X 10.6 - Mac OS X 10.6.3) in one fell swoop. The update includes all of the changes and security updates included in Mac OS X 10.6.1, Mac OS X 10.6.2, Mac OS X 10.6.3, and Mac OS X 10.6.4. For more details on the 10.6.4 contents, see our full coverage.
The update is an 887.37MB download from Apple’s Web site.

Bryan Chaffin
11” MacBook Air 1.6GHz dual-core Intel Core i5: $829.00 Delivered
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Canon imageCLASS Monochrome Multifunction Laser Printer: $129.99 Delivered

An interesting observation. The download is 641Mb in size.
Before the update I had 361.35 Gb free
After the update I have 362.09 Gb Free.
It liberated about 3/4 Gb of hard drive space, actually nearly 1.5Gb if you count the size of the download into this.
cool
(All updates may do this I just never thought to look before)