It can still only run one app, but the 3GS has the latest ARM processor, the Cortex A8 which is ridiculously fast. There are some benchmarks here:
http://www.anandtech.com/gadgets/showdoc.aspx?i=3587
I ran them on my Omnia and tended to be near the slower side on each one. I'm not surprised though, the Cortex is used in the Archos 5 media player which is able to decode HD video onboard (!) as well as the OpenPandora which is designed to emulate console games.
So while the software hasn't gone that far, the hardware is a pretty big leap forward.