Does Linux support the ability to use multiple SSL certificates per IP address? For example, I want use one IP adress to host two different e-commerce sites that have different domain names and use different SSL certificates. Under Windows 2000 I have to use two different IP addresses to this.

Unfortunately, no, but it's not really a Linux limitation but an SSL/TLS one.

You see, the certificate transaction happens before the client has the opportunity to tell the server the hostname of the web site it is trying to reach. Virtual hosts work because the client sends a "Host:" header indicating which hostname it wants, thus multiple hostnames may be served by the same IP. Because of the certificate validation occurring before the client sends the "Host:" header, NameVirualHosts cannot have individual certificates. I may be wrong, but I believe Apache will use the certificate of the virtual host defined first in the configuration file for any SSL requests on that IP.

You can still run SSL on the other sites, but the name of the certificate presented will not match the "server name". This will most always cause a browser warning to the client.