Part of the problem with services like box.net is that what happens when two or more people access the files at the same time? Since each server has its own local copy and then syncs to the cloud there is the opportunity for information to be lost. If two users are working on the drawing at the same time, User 1 saves the drawing and then User 2 saves the drawing it will overwrite User 1 modifications. If you just use the service as a file depository and do not use for active drawings then I think they are great. I use yousendit.com for the same thing and place all of my files in the clould. I sync certain folders to each of my pc's and have access to all of them at any time. internet connection required of course.
100% Agree with Keith. Great as a backup tool, not as a working tool. Fails when working with Word and Excel files too. Once you can expect multiple people to want to open the same file at the same time, you'll get conflict files and it all goes bad.
Using Inventor 2013 and Vault Basic (New to Inventor)
6 years Solidworks (v2006-2010)
10 years Pro-Engineer (v13-WF2) w/ Intralink (2.0-3.0)
2 years of Mechanical Desktop
AutoCAD since R12
First professional CAD: DrafixCAD