By Katie Marsal

Published: 08:55 PM EST

Although announced less than two weeks ago, screen captures of a Mac OS X Snow Leopard test build show the ability to create web apps in Safari 4 and an update to Address Book with hooks into Microsoft Exchange.

The new test build, documented by German website Apfeltalk (with translation by Engadget), offers a "Save as Web Application" menu item in Safari that creates a complete version of the website that can potentially be used offline and without the overhead of normal web browser.

Similar to web app icons for the iPhone's home screen, the feature is intended to improve access to online productivity apps like Google Docs or Photoshop Express, which can substitute for some dedicated programs on the desktop.

The web browser is also expected to implement a few additional changes including SquirrelFish, a new Javascript engine that promises much faster performance than the current Safari 3.1 engine and will be key to web app support.

Snow Leopard also already includes a test upgrade to Address Book, dubbed Address Book Exchange Preview in the early build, that adds a connection to the Microsoft collaboration format. Once the user is logged in, contacts stored on an Exchange server are synchronized with the Mac at user-set intervals.

Few other changes are immediately evident and are often only visible through different version numbers; the latest iteration of Snow Leopard currently uses QuickTime 7.6 rather than the QuickTime X overhaul promised for the final release.

More changes are expected to surface before Snow Leopard is released in mid-2009.