I just upgraded my beta version of Visual Studio 2008 SP1 to the final (rtm) version, and noticed that code that used to work on the SP1 beta no longer did. The offending piece of code was a LINQ query where I was querying out some stuff from my entity model.
The error message I was getting said "The ntext and image data types cannot be used in WHERE, HAVING, GROUP BY, ON, or IN clauses, except when these data types are used with the LIKE or IS NULL predicates." which didn't really make sense, since I wasn't using ntext for any columns.
As it turns out, there is a bug in there, and for more information (and a workaround that's a bit of a pain in the butt) please look here: http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=3746251&SiteID=1.
I'm not sure if this problem exists only with the Entity Framework or in any LINQ to SQL Compact scenario as well, but I'm assuming it's there in both.
This is really not so great, because we have a couple of projects at work where we're using SQL Compact and LINQ together, and we've been hoping to go to Visual Studio 2008 SP1 because of some of the new features in WPF and other things. So I really hope there will be a fix for this.