Rex Black posted Does Citrix Think Software Compatibility Testing Is Unnecessary? about my comment on IE9 with Citrix for one of his webinars.
Recently I also read that Kindle Cloud reader works with WebKit browsers because it uses the non-standard WebSQL SQLite database. That’s why it doesn’t work in Firefox
or IE9. WebSQL was abandoned by W3C in favour of IndexedDB.
It shouldn’t be that hard to support or test for multiple browsers. There are many solutions.