Just to announce that the Sql Server 2005 Integration assembly is no longer beta. The final version has some data validation features that were not present previously.
More important is the ability to work with binary data. Previously line were stored as strings and they were parsed using regular expression. Now there is also the option to save lat,lng data in binary form (Varbinary data in the database). I did some testing on this and there is no significant speed advantage, but it is much less error prone. The downside is of course that the line data cannot be manipulated in directly in the database manager. So whatever format you choose is up to you.
The GooglePolyline and GooglePolygon classes both have the static (Shared) methods WritePointsToByteArray and ReadPointsFromByteArray to handle the conversion from byte array to List<GoogleLatLng>.
Users who have purchased a license for the Google Maps .NET Control can download the assembly here.