One of the true failings of Ajax is that it's a mashup of a number of technologies that relies on various versions of code to support various browsers - that it's not complimented by a single cross-platform runtime like the Flash Player. Google's popular Gmail is likely to be the most used Ajax application today, and like other Ajax applications it suffers from the inability to offer true cross browser support, especially for Safari.
Since its launch two years ago Gmail has never offered proper support for the back button on Safari. I use Gmail for all my mailing lists because of the power of the search that it offers and the fact that I can access those lists from any browser.
If I were to search for a particular Flex topic within the FlexCoders list that I'm subscribed to (that mailbox has 13,000+ threaded posts in it at the moment) and then try out some of the results that I get I'm fine. If I were to hit Safari's back button mistakenly thinking that I was going to return to the list of search results I'd instead be returned to the mailbox itself. Do that in FireFox on the Mac and I'm returned back to the search results, as the application should be expected to do.
I've double checked this very recently as I've been investigating Ajax for some writing that I've been doing, the back button was broken in Safari last week. Tonight I forgot what I was doing and discovered that Google have added a hack to the Safari version of Gmail to address the back button problem.
How would you address this problem yourself? Make the feature work, that's what I'd be trying to do.
How did Google fix it, simple - disable Safari's back button so that it doesn't work at all when using Gmail!
I guess that I won't be frustrated by the back button not working properly any more, now that it doesn't work at all.