It is not missing. It is just that there is nothing out there that uses the newest version. Go under Control Panel>Devices and Printers. You will see the Microsoft XPS Document Writer. That is the same thing.
You are using the Beta. That is not the final product. The Beta versions do not contain every single thing that the final version do. These are only versions used to test that the new additions work properly.
I can verify that the XPS writer is included. I know this because i am using the Final Version and i have the XPS Writer.
That is the Final Build of Office 2010 and that is the view of the Devices and Printers area. Sadly you wont find this info, cause everyone else is running the Beta as well and they get the same thing you do.
Also Google will NOT get you results for Windows products that are extremely accurate. Google does not spider any of Microsoft's sites. So you only get 3rd hand information from other forums and sites. Never any real information from Microsoft by using Google to try and find answers.
To take this further, the Document Image Writer died before Office 2007 came out. With Office 2007 it was renamed to the XPS Document Writer. Directly from the Office website. Along with this information, the Document Image Writer is not available for any 64 Bit version of Windows as well.
So you will have to try using OneNote or some other tool to do what you have previously done with DIW.
Sorry that i failed to mention that the Document Image Writer was renamed at first. It wasnt until i did research on the Office website, and realized it myself, that the item was renamed that i commented on it. I thought it was in the Beta, but since it has been a while since i used it i couldnt confirm it.
The XPS Writer should do the same exact thing. As far as i know, it was just a name change that occurred.
I think you are right on the money, it seems for all intents and purposes, it does the same thing...too bad there was not some announcement. Who knows, maybe there was just one shot of bourbon too many