By Aidan Malley

Published: 08:50 AM EST

Although Apple touts several key features for its latest Mac OS, numerous minor but welcome changes have already been discovered, AppleInsider has learned.

People familiar with the current test version of Mac OS X Leopard report that, like earlier major upgrades to Apple's core software, a host of small but useful updates will accompany the final release.

The most apparent upgrades involve media playback tools, the sources say. A new version of QuickTime included with Leopard will reportedly allow full-screen mode without a QuickTime Pro key, echoing the feature added months before to iTunes. DVD Player will also see a major update with an HD options pane for Blu-Ray and HD DVD discs as well as the opportunity to add DVD cover art and change movie region support on the fly.

Sun's recent ZFS will also appear in a limited form as promised, those aware of its inner workings note. Despite Sun CEO Jonathan Schwartz' protests to the contrary, the unique file system will appear as a non-default, read-only format out of the box with write support possibly arriving as a separate update in the future.

Regardless of access, however, ZFS in Leopard will support some of the trademark features, such as instant and low-storage "snapshots" of a disk volume, and cloned copies that can be modified with only a small penalty in terms of disk space.

iChat may also have received a substantial upgrade, according to the claims. Those contacts with mobile phone numbers can be sent an SMS text message -- spurred in part by a desire to integrate with the iPhone. Google's influence is also allegedly present in the instant messaging app and will let Google Talk accounts mix with today's AIM, Jabber, and .Mac users.

Lastly, this emphasis on expanded options may also filter its way into many of the smaller apps, based on the the new information. Users choose the default IM program, similar to the way Safari is used to choose the default browser, and will also be able to explicitly share more than the Public folder on a network. Even Dictionary will have the choice of switching from the Oxford dictionary to Wikipedia, the sources added.

And while it's clear from the impressions provided to AppleInsider that some polish is still needed to refine these features ahead of the October release, those that are reportedly present are comprehensive enough to indicate that Apple will focus many of its less conspicuous efforts on the user experience, rather than on background technology alone.