I tried the simple scenario on my VM Win2k3 as follows:
1. Install SQL Server 2008 RC0 (full install)
2. Uninstall SQL Server 2008 RC0 (full uninstall)
After the full uninstall of RC0, I can still see VS 2008 Shell, Visual Studio Tools for Applications and SQL Native Client on Add/Remove Programs. Those components are Redists. Therefore, after the uninstall, other software still need them.
It is so interesting to know this scenario.