Yes, IE9 has finally shipped. It is amazing how many versions of IE we have shipped in the past few years. The browser just keeps getting better and better. I have been running IE9 since an early beta, and it has been rock solid for me. I always discounted the claims of other browsers, about how speed was important. I figured speed never seemed an issue to me. I do use other browsers (not full time), and they never seem to grab me.
To download IE9, go to www.beautyoftheweb.com. While you are there you should check out some of the HTML5 and speed demos. Then try them on your other browsers. What I like about the site is that is shows some compelling uses for HTML5, beyond just being a new spec we can get excited about.
I am proud of how we as a company have worked with the industry on HTML5, sitting on the board, and contributing over 6,000 test cases. These ‘unit tests’ are important because they lend a certain degree of baseline to the technology, and helps avoid the old saying : “Everyone has a different implementation of the standard.”
I particularly like the pinned sites, where I can drag the icon of a site to my Windows 7 task bar. 
This turns the web site into an application, giving me context in the task bar, with jump lists, and shortcuts. For example, Groupon, one of my favorite sites has already implemented this. In their jump list they show the deals for the day, and make it easy for me to click through to see them.
If you want to learn more, as a developer, on how to get more out of your browser, check out IE 9 Tech Center. Come up with a great way to push the limits of your browser, without requiring a plug in and you can enter our contest, Dev Unplugged.