Did you know that Online Collaboration features of Adobe Acrobat integrate very well with SharePoint? Use the shared review feature of Acrobat as the approach to online collaboration. It synchronizes comments and has features to simplify commenting for users.
In shared reviews, reviewers publish their comments to a remote server, yet retain a copy of all comments both in a local cache and within any locally saved copy of the PDF file. Comments are synchronized between the locally saved PDF document and the local cache when the file is first opened in Acrobat, and thereafter comments are synchronized between the local cache of each reviewer and the remote server asynchronously even if Acrobat is not running. This allows reviewers to work disconnected from the review server. A shared PDF document contains the names of all of the invited reviewers, the remote location of the review comments, and information about the initiator.
So, what version of Acrobat do you need? Version 7,8 or 9 would be perfect. However, we also got this working with version 5 (using WebDav). In version 7 or later I would recommend to use the network folder repository type for SharePoint.
Now, how does this work? First of all you will need to configure Adobe Acrobat so that it knows where to store your comments. There are many ways to configure Acrobat. Through the installshield tuner, through FDF files (which contain Javascript), through embedded Javascript or manually.
Let me describe the manual configuration method: Start your version of Acrobat (needless to say that the Reader version does not allow you to collaborate, you will need standard at least). Go to Edit –> Preferences –> Reviewing. Now select the Server type as Network folder as the repository for comments. Why a network folder? It is the easiest way to configure and does not require 3rd party tools. However, remember that with network folders all users need to be on the same platform (eg. Windows or Mac-Os) due to hashing algorithms used. Now, enter the UNC path of the document library where you would like to publish your comments to. Eg. \\mysharepoint.company.com\sites\commentsLib.
That is it. Imagine you open a PDF file using Acrobat. Next you would start the reviewing process. You upload the PDF to a shared SharePoint document library, add your comments (like an Approved Stamp) and save them. Comments will be send to other reviewers you specify during the publishing process. What happens on the SharePoint side? All comments will be stored in the document library you have configured. This should be another library then where you have stored your PDF documents. You will see that Acrobat creates a hashed folder for each document. That folder contains at least a info file with the name of the document and one file per user that holds the comments. When you now open the PDF it merges the comments from all users at run time so you will experience true online reviewing.