UPDATEI have had a few questions about this so I thought it would be easier to post the details for everyone.
There is now a V4 mapping disc (Western Europe) available for the RNS-510, which from what I have seen is just a mapping data update.
The format of the disc is slightly different to the v3 discs so some of the process for creating POI's for speed camera's is different.
It is possible and I have been able to in the last couple of days to get it working, but it required a patched version of the POI inspector. These details can be found in various threads over on VWNavi.com. Be aware most of the details are in dutch or german so it's no an easy process.
An new version of the POI Inspector program is due out shortly with some additional features so the whole process should get easier in the near future.
HTH
StevePG