While in most cases the basic migration steps of converting the database and recompiling the application code will suffice, there are a number of new features and behavior changes that should be taken into account to get the best results out of a migration to OpenEdge 10.These considerations have been documented in the Whitepaper "Upgrade from V8 and V9 to OpenEdge 10", which can be found on the communities website (
http://communities.progress.com). This Whitepaper captures some of the best practices and key issues to consider when upgrading, migrating or transforming your application from Progress v8 or v9 to OpenEdge 10. The whitepaper is organized by topic area and provides links to relevant technical Support articles and product documentation to provide further details.
Also, for customer using distributed applications that includes using AppServer, WebSpeed, WebService also lookk for the "
Exchange 2008 Breakout Session" OPS-7: Migrating your Distributed Application from V9 to OpenEdge® 10 with (Almost) No Downtime" for helpful tips on how to plan such migrations. 
