I'd think that fractals which are ensentially mathematically generated images, can be produced in 2 dimensions, 3 dimensions, and likely even 4dimensions (considering that the 4th dimension would be Time or a quantum state, or a phasic property).
Here are a few sites I found interesting while I was google-pondering your question arb:
3D Fractals
3D Fractals Gallery
3D Fractals
3D Fractal Landscapes
it goes on... just google "3D Fractals"
Heres a few pages of interest on 4D Fractals
http://www.geocities.com/joke_dst/tcprenderer/21.pdf
http://www.superliminal.com/fractals/
I even came across a theory that considered wheteher or not the Universe could be expressed as a fractal image... it has uncanny similarities.
Mike.