Dubstep Question???

LFO's mate.
Assign an lfo to control the filter and sync the lfo to say 16ths
8ths whatever sounds good to you.

(this is just one way to acheive the effect)

There are SO many ways to do it... some already mentioned.
 
Others:   Side-Chaining using a gate key signaled (like a kick trigger)
                Plugins that do it for you (FX plugins with sequencers like Effectrix for example).
                Side-Chaining using a compressor with a key signal that is tempo-based (a kick for example)
                Using a plugins built-in modulation functions
 
The list goes on...
 
Using the LFO's is probably the easiest and most direct method - especially if you're new to some of these techniques.  And it's usually easy to setup within many plugins.
 
 

Dubstep is a club genre that's pretty popular in Europe. Here's an example: Benga and Skream - Walkin Bass  and a less othodox one: Burial - Archangel

LOL If you run out of ideas for a new tune sometime it can be great to just try to emulate somthing you normally wouldn't come close to. Or just because it's fun to widen the horizon.

Just because it's fun then...

Two-step is popular here!

Although you could make wobble bass in Dimension pro, I'm sure most would agree there are better synths that come with sonar to use. Pentagon is probably the easier route but Z3ta is fairly simple once you get used to the interface.  here is a tutorial on using Z3ta to make wobble: http://www.youtube.com/watch?v=Uxfm26TGjlc

"New question: How does one create the tone slides? (where the pitch of the wobble bass slides - usually down) "....... me personally id set an arp up in z3ta 2, set it to down (2/3 octaves, maybe 1/4 or 1/8 th notes) and put portmento on it, and obviously with the lfo sent to cut off to get the wobbles in the first place, set the tempo sync the same as the arp !! EDIT: i take the arp bit back lol just tried it doesnt sound right lol, i think to get that effect you might want to try using the pitchbend automated slightly to get that

for z3ta 2 that patch by the way

in z3ta+ 2 what i usually do is map a slider on my keyboard controller to all oscillators pitch in the mod matrix for the pitch slides.  range is full and you csn play around with curves. the other cool thing is setting up six different lfos then in the mod matrix you map the source to a midi controller like a slider shift right click. then set the min vaalue for source ot off and the max to lfo6. then you use the slider to switch between lfos. then map six more sliders to each of the lfo sync parameter and you have some badass control rightt there.