According to sources, the first external pre-release copies of the update, Mac OS X 10.4.7, began making their way into the hands of Apple developers on Monday.
The software builds were labeled "Mac OS X 10.4.7 build 8J111" for PowerPC Macs and "Mac OS X 10.4.7 build 8J2111" for Intel machines, those sources said.
Mac OS X 10.4.7 will be the seventh maintenance and security update to Mac OS X Tiger since Apple first shipped the software last April.
Already sources claim the early builds of the update have patched "over 60" significant issues not addressed by Mac OS X 10.4.6, the most recent release of Tiger.
Specifically, Apple is reported to have asked developers to focus their testing efforts on Mail.app, Safari, Syncing, and iChat. The company also indicated that Mac OS X 10.4.7 would offer improvements for its professional photography customers who are running Aperture.
Those developers testing Mac OS X 10.4.7 have commented that the initial builds of the update are rather stable for an inaugural developer release. They list only a handful of known issues related to the Calculator and Mail.app applications.
Apple is expected to release the software update later this spring, ahead of plans to unveil its next-generation operating system overhaul, code-named Leopard later this summer.