By Katie Marsal

Published: 01:00 PM EST

Apple this week is believed throwing the finishing touches on Mac OS X 10.5.6, the last planned maintenance and security update for Leopard during the 2008 calendar year.

Developers on Wednesday were reportedly equipped with build 9G55 of the software, which included no noticeable changes from the build (9G52) that was distributed five days earlier.

Separately, people familiar with the matter say Mac OS X 10.5.6 Server was also synched up with the client software and now carries the same build number, typically a telltale sign that both distributions are being primed for a public release.

Another sign of a near immediate release is that both the client and server distributions currently reflect no known issues, those same people say. The client software reportedly weighs in at around 370MB while the server update is a bit heftier at 470MB.

Previous coverage of Mac OS X 10.5.6 reveals the client update to bundle more than 100 bug fixes and enhancements. One specific focus has been improving MobileMe's automatic syncing, particularly on portable computers connected to networks with medium to high latency or constrained bandwidth.

Throughout the beta test, the Mac maker had also been requesting feedback on MobileMe syncing from users who may reside behind firewalls, asking they watch for excessive syncing or abnormal syncs.

Apple began external testing of Mac OS X 10.5.6 in late October. At the time, it was noted that a list of focus areas presented to developers was the most extensive yet for a Mac OS X 10.5 Leopard maintenance release. In total, more than 80 core system components had seen modifications and were in need of evaluation.