Because of the advances in MATLAB, this may not be a useful hint anymore, but give this a try sometime:
Now, I believe there's a way to do this without having to plot first. That is, I think there's a way to plot to PDF without first generating that figure.figure(1);
set(gcf, 'Visible', 'off');
print(gcf, '-dpdf', 'figure1.pdf');
system('open -a Skim figure1.pdf');
What's cool about this is that any future updates of the PDF will cause Skim to update automatically. Therefore, Skim becomes your plot viewer. That might be nice, right?