Cisco has VSS (on 6500 class) and H3C has IRF; allowing you to virtualize 2 or more physical switches/routers in an active/active configuration where you can use all links and terminate LACP aggregates between the two devices. Is anyone using this or similar technology from another vendor? any recommendations or comments would be appreciated. thanks very much for your time!
-g
Juniper also has Virtual Chassis support on the EX-series. The MX also supports active/active multi chassis-LAG. It works as you would expect, as you setup an ICCP link between the MX's.
Truman
I seem to recall that both of these implementations suffer from some significant limitations around how/what you can do with them, as well as HA options...though that's all I can remember from digging into it (enough to realize it wouldn't work for us) last year.
OTOH, Raptor's "virtual chassis" magic (while it has its own issues...) didn't have these problems. 
BTW, with VSS you can only combine 2 switches.