[Uncle Peter]

Enterprise type managed switches have also assimilated many of the layer 3 functions associated with olde worlde routers and will support concepts like routing and forwarding between vlans and conversely provide a means of segregation between vlans.

So if you were an IT services provider with a shared infrastructure a very basic scenario might be that a primary core switch is deployed to terminate many customer networks via VPNs/MPLS for example, maintaining separate routing tables for them which direct traffic to the appropriate destination in your data centre or shared service environment.