Box.net added a really cool, and useful collaboration feature to its online storage service yesterday. Any user can right click a folder and choose a new collaboration option that lets them invite anyone to gain access to those files, either as an editor or viewer. Box.net has always had the option of linking to the file, or sharing a grouping of files with everyone, or a just a small group of people via its premium service and snazzy widgets; however, this new addition is more advanced.
Once a user becomes a collaborator, the shared folder will show up in their Box.net storage area. To keep user sanity, the service now includes versioning. This lets users know when the file was last edited, and by which user. If a file that been edited, users will see right away how many times it has been changed. They can go back and either download the old version, or revert it over its current state. This is going to be hugely helpful with image files for which there have been editing tools using Picnik and Snipshot since the launch of OpenBox, Box.net's API platform back in November.
There are few small caveats to the service. One being that collaborators need to have a box account, and the other that free members can only have up to three shared folders at a time, and don't get access to the versioning records like premium users do. I don't think either is a deal breaker (Google approaches collaboration with Docs and Spreadsheets in the same manner).