As long as you're not planning any heavy HD content rendering while on the road, a MacBook with 2 GB RAM would round out your system nicely.
The MacBook would be perfectly fine for showing off your work and most other portable essentials.
You still really need a pro desktop for any heavy lifting and for the storage if you're taking full advantage of what Final Cut Studio has to offer.
If you're thinking destop replacement in a portable, I'd wait for the Penryn
processor models when they make their debut.
I wish we could say that Apple will release a smaller MBP soon with any confidence, but that is also a possibility that would be perfect in your situation.