Apple has recently released the first public version of Safari 5 with some cool new features, which make it very tempting to download and install. But I would like to recommend caution before you click on that download link.
We are aware of several problems with Safari 5 -- some of which can break critical features in Sente. And it is likely that there are more problems yet to be discovered.
The biggest problem we have seen is that installing Safari 5 on systems running OS X 10.5 will simply break web browsing in Sente. Attempts to load many web pages in Sente's embedded browser will cause Sente to crash. It does not matter whether you are actually running Safari 5, just whether you have installed it or not. There is no approved method for uninstalling Safari 5, so you will be stuck until you either upgrade to OS X 10.6 or Apple fixes the bug. We are not aware of anything we can do to fix this problem.
The problem is that installing Safari 5 is not like installing a new version of Firefox or any other browser. Installing a new version of Safari changes OS X's internals for web access, the very code that Sente and many other applications depend on.
I have some confidence that Apple will address the problems with Safari 5 quickly, but it seems that their public debates with Adobe may have lead them to rush this out the door without as much testing as it deserves, given how critical Safari and WebKit are to real world users.
I am sure that many of you will have found this post only after installing Safari 5 and experiencing problems. The best that I can offer for the problems that we are aware of is to consider upgrading to the most recent version of OS X. Even if this does not solve the problem, it makes it far more likely that you will see a quick fix from Apple.