I looked at the preferences of the new beta version of Safari 4 seeded to developers. In the previous version we could select or not 64-bits addressing via get-info. This option disappeared in the last version seeded, and when looking in the info.plist file, one can discover that 64-bits requires at least Mac OS X 10.6...There are currently two hypotheses for this change:
It might indicate how Apple intends to promote/open 64-bits for previous version of Mac OS X...
- Apple spotted problems for running 64-bits Safari 4.0 on current and previous version of Mac OS X, and will then restrict its compatibility with Snow Leopard while waiting for a patch for making it fully functional on previous OS X.
- Apple aims to lock Safari 4 to Snow Leopard to further define the difference between the current version of Mac OS X and its future evolution planned to be released by the end of the year.
