Spanglystuff (http://spanglystuff.blogspot.com/) has made some really beautiful examples.
This has petals made with single squares of fabric.
This has 2 fabrics on each petal.
And these are more whimsical.
And she has a tutorial at http://s91.photobucket.com/albums/k297/JensMum/?action=view¤t=MVI_2505.flv
I also found a youtube tutorial at http://www.youtube.com/watch?v=BJZFqOLKRNo&feature=related
I only had a few to spare to try out the first technique, but this is my first rough attempt. Looks yucky next to hers, but I'm liking it enough to give it another try.
Gotta go. DH will be here soon and dinner's not ready yet!