Using a wildcard inclusion managed path at the root of a web application in WSS 3.0 and MOSS 2007 has limited support, it is recommended to migrate the affected sites away from this structure.
Using a wildcard inclusion managed path at the root of a web application in SharePoint Foundation 2010 or in SharePoint Server 2010 is not supported. This configuration is not explicitly blocked by the user interface or the command line tools, however there are several features in the products which will not work properly in this configuration.
This configuration is not supported even if the web application is using classic Windows authentication and will not use claims authentication in the future.
It is not supported to in-place upgrade a WSS 3.0 or MOSS 2007 farm which has a root wildcard inclusion managed path, however this is not explicitly blocked. It is advised to resolve this problem before attempting the upgrade. It is not supported to upgrade a WSS 3.0 or MOSS 2007 content database using the database attach method which was using a root wildcard inclusion managed path, although this is not explicitly blocked by the product.