Mary Jo Foley blogs today about an Oracle 2 OBA (Office Business Application) competition.
If you haven't read much about OBAs yet, she points at Mike Walker's blog which has some articles about what is an OBA. But I think in most cases if you are doing VSTO development you've built an OBA--although you may not have used all the richness of the Office platform though so it is interesting to see things like the logical diagram I posted about earlier to broaden your perspective of what is available to an OBA. OBAs become very interesting when they integrate with SharePoint, Line of Business data, and use the "context" concept to put your business data at your fingertips at the right time--for example, if you are editing an expense report in Excel an OBA would be smart about showing you commands relative to posting that expense report to a back end server.
I also like the phrase "Office Mashup" that Mary Jo uses in her article. I've heard this phrase internally at Microsoft and in other channels--not sure who invented it. But I like it because some Office applications you build aren't necessary bringing line of business data into Office like an OBA does but are instead more about personal productivity or bringing non-business data into Office in the right context. For example, I've seen some interesting mashups with Outlook and Live Services like Windows Live Maps--in fact I demoed a mashup like this at the MVP Summit and VS Live. My demo also extended the Outlook RSS reading feature by adding a forms region that displays in the reading pane to show you the full web page for an RSS article you've brought into Outlook--a "mashup" that enhances personal productivity when using Outlook RSS support. I recently heard of a demo app built on my team that integrates Outlook with Facebook so when you are composing an e-mail to a friend in Outlook it uses Outlook 2007 Forms Regions to display the most recent pictures your friend has posted. We have another VSTO demo app in Word that integrates with Amazon web services to help you to build rich wishlists in Word that you can print and track. These are all pretty cool ideas--being inside an Office app but getting access to useful web services is more useful in some cases than purely web based mashups doing similar things.
[Update: Added link to 02OBA Challenge Website: http://www.o2obachallenge.com/\]