Many an oldschool developer has been put off from joining the "RIA" world because data access through web services is a comparitive pain in the arse compared to old school ADO.Net. Some smart guys in Canada might be changing the equation (hopefully). I haven't used Laskarzhevsky Software's free Silverlight DataSet control yet, but it looks promising. Check it out and let me know what you think.
Laskarzhevsky Software Inc