Geocoding: Can you only use it for contacts?
If this is a situation where the Case is related to a house/building site and hence you want to be able to map 'all cases' then getting Address fields and Lat/Long fields would take significant coding I think. 

Workarounds? If you already have an Organisation Contact sub-type to represent the dwelling then you can get the Lat/Long for that and hence create the map filtering on those which have current Cases.