very good idea.
it seems it might be Cisco model dependent. for instance this switch offers that MIB http://tools.cisco.com/Support/SNMP/do/BrowseMIB.do?local=en&step=2&mibName=ESSWITCH-MIB
and here's the Cisco MIB to the VLAN table http://tools.cisco.com/Support/SNMP/do/BrowseOID.do?local=en&translate=Translate&objectInput=220.127.116.11.4.1.418.104.22.168.22.214.171.124
but it may only be Cisco Fast Switch (Grand Junction) switches which support this at all http://www.cisco.com/en/US/products/hw/switches/ps591/products_tech_note09186a0080094399.shtml
if you use these models (G2xxx) then you might be able to use UnDP to do what you wanted.
I believe you might be right in that they are independent upon devices.
Works with 3750s. Now to find 4948's.
I'm curious about Switch Port Mapper in ENGINEER TOOLSET.
It includes a column VLANs(Cisco) but I never get anything on any switch model. It is always empty. If you could get VLANs here then you could export an HTML onto Orion.
Maybe someone from Solarwinds can comment on that column and what it does.