To see the new data after the version update, simply navigate to maps.live.com and click 3D. The new data will be live on the site.
Once this period is over, clients that have updated will automatically begin receiving the new data without any required changes or interruptions. You will probably hardly notice, except that buildings of course will load faster. Clients that have not updated will break! You've been warned! The only issue really will be that buildings will not appear, and only if your code is directly adding model data sources.
The exact length of this period is TBD, but probably about a month. Our hope is that most everyone will update by then anyway, because the new version really is better. I will blog a reminder when the date is decided and approaching. As always, let me know if you will need any help during the transition.
In addition, in several samples I directly linked to the manifest files for some resources, like imagery, dem, and models. These are the urls used when creating DataSourceLayerData objects. I encourage you to instead use fwlinks, which are just redirects to the same resources. This will help us update data while minimizing impact to clients.
Edit: took down the traffic link. If you are interested in traffic data, please see here: http://msdn.microsoft.com/en-us/library/bb877877.aspx