With BC 4.0, I put in a couple starting and arrival times. An exported gpx showed the XML code:
<trp:Trip>
<trp:TransportationMode>Automotive</trp:TransportationMode>
</trp:Trip>
and
<trp:ViaPoint>
<trp:DepartureTime>2012-08-13T14:00:06Z</trp:DepartureTime>
<trp:StopDuration>P0Y</trp:StopDuration>
<trp:ArrivalTime>2012-08-13T14:00:06Z</trp:ArrivalTime>
<trp:CalculationMode>FasterTime</trp:CalculationMode>
<trp:ElevationMode>Standard</trp:ElevationMode>
</trp:ViaPoint>
When imported into MapSource and Saved as a gpx from MS, these fields are lost.
If you use the Trip added data in BC, your routes can be opened in MapSource, but you lose this trip data if you Save in MapSource and re-import into BC.
(No bug here. Just something of which to be aware.)