There is one nifty trick I can no longer do in SQL Mobile - writing to an IDENTITY column. I just hope this is Beta behavior, otherwise it will break my products.
SQL CE 2.0 allowed consumers to write on IDENTITY columns, a feature that enables copying desktop databases. The table is created on the device with the IDENTITY column set at the given seed and increment. When copying the table data, the column values are forced (the OLE DB provider complains mildly) and the resulting table behaves exactly like the source one. Interestingly, both Jet and SQL Server allow this so why wouldn't SQL Mobile allow it as well?