iCustomMapping LinkFieldValue errors in Sandbox solutions

Problem:  I was trying to use the iCustomMapping interface to add additional columns of type LinkFieldValue to a sandox solution I am getting the error:
{"Type 'Microsoft.SharePoint.Publishing.Fields.LinkFieldValue' in Assembly 'Microsoft.SharePoint.Publishing, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' is not marked as serializable."}

Initial Hypothesis: I could not see why I as getting the error but a Google search found me a post that gave me the answer.

Resolution:  Change the code from
SPListItem item = (SPListItem)listItem;
this.ContentLinkField = item["LT1"];
To:
SPListItem item = (SPListItem)listItem;
string value = item.GetFormattedValue("LT1");
this.ContentLinkField = new LinkFieldValue(value);

More info:
http://www.alexbruett.net/?p=255