Apple has posted two software updates through its Software Update utility and its support web site. The first is an update for GarageBand Jam Pack 4 Symphony Orchestra to version 1.0.1 and the second is a security update for the iSync utility labelled "2005-004".

Notes that Apple provides for the GarageBand Jam pack 4 update:
This update addresses isolated issues with the sound quality of some Software Instruments when used with GarageBand 2, Logic Pro 7, or Logic Express 7.

Notes that Apple provides for the iSync Security Update:
Delivers a number of security enhancements and is recommended for all Macintosh users.
This update includes the following components: iSync

More information about Mac OS X security updates can be found here.