The SAGE staff pulled down the booth for that anyway, so it's no big deal really.
Apart from 2009 when v2.0 was released, SRB2 2k3 was also released at SAGE (in 2003, obviously) so news archives and other old records tell us. Demo 1 had a SAGE video too but I don't know if that got a booth or not.
Going back through Wayback Machine I've also learned:
* SRB2 developers and other people have been involved with various past SAGEs (SSNTails I think helped with hosting the site one time? relying on memory here)
* we once had an SRB2 Tournament thing in 2008, but apparently that completely flopped (oh well)
* I think even BlazeHedgehog's SA-SRB2 mod was mentioned at SAGE one year? I probably need to double check that one
Basically it's the version of SRB2 that introduced weapon rings (in the same way they were for 1.09.4), chaos mode (which was removed much later), digital music, and other minor useful changes and such.