There's one more minor change as well -- there's now a + symbol at the far right of your tabs, which when clicked upon opens a new tab.
Beta 1 (and Beta 2) also make a nifty improvement to the Smart Location Bar (which some call the "Awesome Bar"). Normally, when you type text into the Awesome Bar, it shows you a drop-down list of URLs you've recently visited, as well as URLs from your bookmarks and narrows down the list as you type in more text. With Firefox 3.1, you can control the Awesome Bar and the results it displays by adding special characters to the end of what you type. You can have the Awesome Bar only display results from your history list, results from your bookmarks, results from the URL itself or results from pages you've tagged. For example, to only display results from your history, you'd type in your search terms and then a space, followed by the ^ symbol.
The bottom line
Beta 2 of Firefox 3.1 is fast and stable and incorporates two important changes to the browser: a private browsing mode and a sped-up rendering engine. I used it without problems or crashes on two different PCs. Those who want to see the future of Firefox would do well to download it now. When the final version is released, it will be a must-have download.