Twitter's branding shows in the new IE9 frame when a user visits the site.

Microsoft this morning is unveiling Internet Explorer 9, the next version of its web browser -- with a streamlined, translucent appearance and the ability for web publishers to put their branding in the browser frame when users visit their sites.

The company is taking the wraps off the design and announcing the first public beta of the new browser at an event this morning in San Francisco. Microsoft says sites including Twitter, Facebook, Amazon.com, and many others are already on board to take advantage of new ways to integrate their services into the browser.

Among other changes, the new IE combines the address bar with the search bar, following the lead of Google's Chrome. From a Microsoft news release, here are some of the new IE features.

Pinned Sites. With Pinned Sites, a user’s favorite websites can be accessed directly from the Windows Taskbar without having to first open the browser, making it quick and easy for users to get to the content they care about. The site’s branding comes through both in the icon and in the site colors in the navigation buttons.

JumpLists. JumpLists offer a quick and easy way to get to a common website task without having to first launch the browser. For Pinned Sites where developers have created JumpList capabilities, users can quickly create a new e-mail message, check their inbox, change the music station, accept a friend invitation or see breaking news. The possibilities are endless.

Tear-off tabs and Windows Aero Snap tabs. Users often need to use more than one website or page to accomplish a task. Tearing off a tab by dragging it away from the browser and using Windows Aero Snap enable users to show two sites or pages side by side. Users can compare products from different websites, watch a video while reading e-mail, or look at a map while reading an itinerary for a trip. To tear off a tab and snap it, the user simply clicks a tab and drags it to the edge of the screen. Content on the site is rendered continuously, and videos continue to play when snapping a window in place, providing a fluid experience just like a native application.

The company previously showed off changes under the hood in IE9 including hardware-accelerated graphics and support for HTML5 video and graphics.

Microsoft is attempting to build new momentum for Internet Explorer, which has experienced steady declines in market share in the face of competition from Firefox, Chrome, and others.

A live stream of this morning's event is available here.

Download the beta here.

Update: Here's the take from Hakon Wium Lie, chief technology officer for browser maker Opera Software of Norway.

IE9 is a significant improvement for Microsoft, and today is a good day for the Web. Microsoft has taken on the Acid3 test and the beta version of IE9 has a much-improved score compared (95/100) to IE8, according to Microsoft. As more browsers support more of the same Web standards, Web developers will have an easier time developing pages and apps that work on any Web device. For these improvements to have the most impact, we further encourage Microsoft to release a version of IE9 for XP and older Windows systems even if these systems will not benefit from hardware acceleration.

The new Microsoft browser works on Windows Vista or Windows 7.

Update: Here's the IE blog post on the beta.