This past weekend, I hung out with Zach Saginaw (Frank Omura, Shigeto), Brian Lindgren (Mux Mool), and Jakub Alexander (Moodgadget) and Dubstep / Wobble Bass came up once or twice. So this BML Tutorial is a tribute.
The first video is re-posted from the Dubspot blog and it shows you how to create a dubstep bass in Ableton Live using the Simpler instrument. You can download the wave file used in this tutorial from here. The techniques can be used to get the sound using any synthesizer, just pay attention to the types of waveforms mentioned and what they do with the filter (BP, envelope, velocity sensitive freq).
The second video is something I found on YouTube made by The Synthesist. It shows how to use Reason to Wobble and also offers a slightly different Ableton Simpler approach.