Information from the developer

Testing package which included the v3.0 Vending.apk (Android Market) and the Google Talk with Video/Voice Chat in a universal form that is meant to work on all architectures and DPI's.

After some testing, it was found that the Google Talk app had a number of bugs, it was not included in the main 20110828 package, and instead offered as a separate ZIP.

--From wiki.rootzwiki.com/Google_Apps