Hi,
You can purchase a network card capable of understanding ISL tags, therefore a server can be part of different VLAN's. I have never seen one, though I know Intel sells the "Intel Pro/100 Intelligent Server Adaptor". When using you must configure your port on the switch to be a trunk port. I'm not sure how the OS would handle multiple layer 3 addresses per interface as I have never used it, however,using some protocol without layer 3 features, such as netbeui and you server should see each segment fine.
-Stephen