Please Help: Is WCF Best Way To Update Client "Compact 3.5" db from "Sql Server"???

You could use SQL Server's Replication service. Your SQL Server 2008 would need the replication service installed, I don't think it's selected in a default installation. After that, it's just a matter of setting your SQL Server 2008 to be a data publisher and all compact servers to be subscribers. Here is some information on it:
http://msdn.microsoft.com/en-us/library/ms172447(SQL.100).aspx

My only question really is why not have the client applications read straight from the SQL Server instead of the compact? I've built an application in a very similar environment and that was the route I went. In my case, all data the client requests is considered volatile and usually short-lived. In the event of a row update, the DAL selects a fresh copy, applies the changes, sets LastUpdated if applicable and commits the changes. It's worked out very well.