Wildcard certificates are useful if you have many subdomains that you want to serve out.
Or you can have a SAN/UCC SSL Certificate from a third party for:
- remote.yourdomain.local <-- VPN/RDP access.
With the new announcement that the coming IIS8 will support SNI (http://blogs.iis.net/wonyoo/archive/2012/03/01/iis-8-0-platform-features-for-web-hosters-and-service-providers.aspx), this will probably change the way we apply certificates for exchange and everything else. In the future we could switch from using a Wildcard or UCC to using a single SSL cert for each SSL application we have, and a UCC one for Exchange.
More on SNI in IIS8:
IIS 8.0 support Server Name Indication (SNI), which has extended TLS to include the virtual domain name to be passed from the client at the time of "SSL Hello". This effectively allows IIS 8.0 to enable "hostname binding" for SSL sites, which eliminates the need for having a dedicated IPv4 address per SSL site.