yes, back the day, i had several 3com superstacks, and they all supported vlans. i didnt really have a good understanding of what i was doing, but i had it working well enough that i had the far right 6 ports blocked off completly from the other 18, and used it like 2 seperate switches.
hindsite 20/20, the vlan tagging now sheds light as to how you can have specific ports respond to more than one vlan (and also why the pfsense tags vlans as it does in the setup).