Sure, no prob.
This is the updates parameter of the REST Request:
[{"attributes":{"OBJECTID":403,"CLAIM_ID":"CLM/2010/067368","INSPECT_DATE":1288522800000,"LOSS_ADJUSTER":8,"ESTIMATOR":7,"HAS_REPAIR_COMMENCED":1,"REPAIRER_NAME":null,"REPAIR_BEGIN_DATE":null,"REPAIR_END_DATE":null}}]
Just take a look at the INSPECT_DATE value. I chose 1 of November of 2010 in the DatePicker of the FeatureDataForm and the value stored in the database and sent in the request is 31/10/2010 (12 or 13 hours less).
I think the Silverlight API (ArcGISJsonWriter.GraphicsToFeatureServiceJson method) isn't converting the DateTime value correctly or MapService.Epoch doesn't have the correct 1970/1/1 DateTime value.
Cheers,
Tito Moreira