You may recall that I posted about a data format change for the new version. The final switch-over is going to happen July 9th. If you are still using an old version, models will stop displaying. So upgrade now, the new version is better anyway.
For those already on the new version (assembly version 4), you do not need to change anything at all.
The plus side is that all of you developers have, for reasons of compatibility, been getting the old data for some time now, even if you have upgraded (right now, only Bing Maps gets the new data, everyone else gets the old). On that date you will automatically start getting the new data, and yes you will notice.