Google Docs does a pretty nice job of tracking revisions to a document. In any document, just choose the File drop-down menu and select "See revision history." You're presented with a list of versions and can see which users made changes. You can even compare versions and revert to the version of your choosing. Not bad for a SaaS word processor, right? Unfortunately, it can't match the version control and commenting available within Microsoft Word. TextFlow, available within the Google Apps Marketplace, does a fine job of addressing this deficiency, but one has to wonder about the price and the value add over Microsoft Word.
Let's start with an introduction to the application from the creator of TextFlow, Nordic River.
Pretty cool, right? This immediately solves the problem of editing and reconciling documents to which multiple authors have contributed. Just drag and drop. Interestingly, some of the more sophisticated functionality isn't available within Google Chrome. The application actually informs you that you aren't using a supported browser. One would expect that applications in the Marketplace would be optimized for Chrome (or at least fully compatible with Google's browser).
However, if, as the video shows, you need to collaborate on a Microsoft Office document, why not just use the versioning and collaboration features available within Office 2010? The best of these require Sharepoint 2010, but at $29/user/year TextFlow is about half the price of SharePoint Online and lacks its countless collaboration and productivity features.
On the other hand, Google Docs is no slouch in the real-time collaboration space either. What it lacks in really granular version tracking, it makes up in simple, cloud-based, multi-author editing. In either case, the number with which I struggle is 79. $50/user/year for Google Apps (assuming you're using the Premiere version) and then another $29/user/year for TextFlow. That's now $79/user/year, almost a 60% increase over the original cost of Apps. In some cases, when a product does something useful at a low price (or for free) or when a relatively expensive product does something that no other product can, then I don't have any trouble justifying the cost of the App added to my Google bill each month.
However, when existing versioning in Apps is certainly good enough (especially if you're using the free Apps for Education or Standard Edition) then I have think twice about something like TextFlow, no matter how slick it is. In fact, if you need TextFlow, then you should rethink how you use Google Docs to work together. If you really need to collaborate using Microsoft Word, then you should probably give SharePoint a close look before you even move to Google Apps. It's a free download to take it for a spin.
It's worth noting that TextFlow is half-price for Edu Apps users and free for college undergraduates, for whom the use case of multiple document versions circulating via email is probably quite common. I'd be interested in enterprise users of TextFlow weighing in here, though, to let me know if I've missed something in terms of the real value of TextFlow. For me, my wife, errr, I mean my business manager, gets grumpy when I buy things just because they're slick.