On July 2 2011, there will be no more support in the form of Service packs, Maintenance Release or Security vulnrabilities. You will however be able to call in and get support to fix it if need be.
This might be a good time to think about an upgrade to BES 5 or BES 5 Express.
Tons more info here
End Of Life for 4.1.6 and 4.1.7 - BlackBerry Support Community Forums