MS Office 2010

Microsoft formally released their latest Office suite today, along with 2010 versions Sharepoint, Project and Visio. The product is initially available for purchase by business customers. Office 2010 will be available through retail channels and online from June 15.
http://www.microsoft.com/office/2010/en/default.aspx

So what's changed? Some of the major changes include a new ribbon style toolbar, which is supposed to be more intuitive and the result of extensive customer beta program. Powerpoint will have enhanced capabilities for video management and web-publishing. Outlook has signficant improvements for managing emails, including a 'conversation' view which allows you to follow emails without having to search emails scattered over different folders. Here's some short videos straight from Microsoft giving an overview of the functionality, features, and explaining how things have changed:
http://www.office2010themovie.com/

Microsoft have also been responding to other players in the market, notably Google Docs and other Open-source suites that provide similar functionality. There will be a free starter-edition of Office 2010 which will include Word and Excel, albeit with some limitations such as lack of Macros, menu customisation and pivot-tables for excel. Also released on June 15 will be Office Web Apps, this will provide free web-based versions of Word, Excel, Powerpoint and OneNote. This will give you the ability to collaborate with shared online documents, much like Google Docs:
http://docs.google.com

No Upgrades
Microsoft announced there will be no upgrade versions available for 2010, with the exception of recent purchasers of Office 2007 (between March 5, 2010 and September 2010) being offered a free upgrade.
http://office2010.microsoft.com/en-gb/tech-guarantee/microsoft-office-20...

Is Office 2010 worth it for me?
There's no straight answer unfortunately, unless you're eligible for a student edition a full office suite is not cheap. So the question really is, will it improve your productivity to justify it's cost, and will it enable you to do new useful things you haven't been able to do before. For businesses that already have staff familiar with Microsoft office products, it may be easily justifiable in terms of productivity gains. The best thing to do if you're unsure, is to spend a bit of time looking at Microsoft's videos and features list and see if it's what your after. You may be able to download a beta version (or the starter version) and see how you like the changes to the interface.

If you don't need all the features or are considering other options, there's some well developed alternative products out there, many of which are open-source, there's Outlook competitor made by Mozilla called Thunderbird:
http://www.mozillamessaging.com/en-GB/thunderbird/

And there is also the OpenOffice developed by Oracle and other developers, this is compatible Microsoft office file formats and offers a realistic alternative:
http://www.openoffice.org/