HSRP has nothing to do with servers: it's a protocol configured on the routers where they send keepalives to each other. If one doesn't get the keepalive from the other, he takes over. It can be configured over most LAN interfaces.
While Cisco would love it if everybody used Catalyst switches, you can use any switch (or even hub) since there is no configuration required on the "middle" device. People studying or recreating HSRP configurations in labs use hubs or smaller switches all the time.
