I recently learning about this technique, apparently it's a cross between classical vibrato, pushing the string forward or backwards, and rock bending, bending the string up and down. Basically, you gently puch the string back and forth while you bend it up and down slightly. Steve Vai uses this often, For the Love of God is a good example.

Anyways, I just thought it was pretty interesting, it's incredibly difficult for me, though.
Anybody ever hear of this technique, or have any tips on mastering it?

i learned it by watching Steve Vai Live at Astoria over and over actually, i got pretty good at it, dont know if im doing it 100% right though, best thing to do is practice with your strongest fingers first, and then repeat your normal vibrato so you make sure the sound is different, the circular vibrato has a "Traveling" sound, if you know what i mean.

you know what, you should request a lesson on this

Great idea, just posted a request!

Maybe I should go out and get that DVD... I've been thinking about getting it anyways, how is it? What songs are on it?

There isn't big difference is sound between regular and this "circular" vibrato,in my opinion.
This circular looks "cooler",that's for sure.
You can get same sound with regular vibrato with adjusting right timing and volume of vibrato.

I must admit, it does look awsome when Vai does it. But im working on Muris Varajic Vibrato myself

Combination of different vibrato technique - flashy

I tried to do the circular vibrato but it doesn't work for me, I prefer my "normal" vibrato, but circular looks cooler (as Muris sai)

IMO I can obtain the same sound with circular than with normal vibrato.