Cell doesnt suit very well because of its multiple cores.
You may not have noticed but *all* newly announced or shipping processors have at least 2 cores, multiple cores is coming like it or not.
That said even the control core (the PPE) should be *at least* as capable as a 2GHz G5 - considerably faster than anything currently shipping in this market.
That's before anyone even looks at the SPEs...
The Amiga was always used a lot in creative computing - video, graphics, rendering and to a lesser degree audio. Cell is a perfect match for these sorts of apps.
There's a simulator out soon so you can see for yourself.