Wizards of the Coast made their announcement about the new version of the character builder here. For more information Wizards has also posted this FAQ. The first link includes screen shots as well if you keep moving to the bottom of the page.
Summary - Effective November 16 the character builder will be accessed via the Wizards website. Each of us has a DDI login already and the same login can be used to access the new web-based CB. Apparently there are a lot of customers who "share" DDI logins but it is not apparent if the new tool will eliminate this possibility somehow. It does eliminate the practice of getting a only one-month subscription every once in awhile when someone wants to get the current upgrade only. The existing CB tool will receive no more updates, but I guess will continue to work on your PC if you so choose.
If things work as advertised we should be able to import our current character sheets into the new tool, although for the time being we will have to keep the new sheets on-line as the export feature will not be available yet. They can be printed, so I am assuming I can still "print" to a PDF file via tools such as cutepdf as I do now.
The new CB tool will include all the Dark Sun and Essentials updates, which should catch everyone up on all the latest data and updates. The Monster Tool (MT) equivalent web-based tool is scheduled for release "soon." The tool will require a free MS-Silverlight web add-on so it will work on both Windows and Mac based devices, but no IPhones or IPad's at least for now (no Unix either). To see what others have to say the best article and comment section I have come across so far is here.
My $.02 - Well, moving off the 1980's based client-server technology and moving into a more Web 2.0 based environment is probably the right thing to do. I am sure Wizards has done a lot of testing and load sharing estimation, but let's face it - there are going to be roll-out issues. Take a deep breath, let it out, let's let them resolve whatever does pop up, and then once they get past that they can release the new web-based Monster Tool.
I will no doubt show my prejudice here, but in my experience most DnD geeks tend to be at least above average in computer and/or math skills and have a strong opinion of what they want their game(s) to be. Therefore when changes like this come along the opinions and feedback there from tends to be strong because it comes in an environment for which many are familiar. Wizards can never be all things to all gamers, so no matter what middle road they try to take they will be criticized by some for good reason, but frankly, by many who just want to make noise (try following any of the discussion forums on Wizards to see what I mean).
I am sure there will be much more discussion of this over the next few weeks, so stay tuned.