Update: TeX Equation 2.0
Since the date TeX Equation came out, our users have been asking for PDF output support. Now I am very happy to say that this feature is finally implemented in the latest update. When you copy the equation image, you are actually copying generated PDF data instead of PNG image. (For existing equations, you need to "touch" the equation text by appending one whitespace or two so that the engine has a chance to regenerate.) Now go to the Pages or Keynote app, and paste it. You will be able to scale the equation to any size you want, and it should look as crisp as possible at any size! Another big change is that we are now using LaTeX syntax instead of Plain TeX. This may bring some inconvenience to old users initially, however, I believe the troubles will be outweighted by the huge advantages brought by LaTeX and AMS Fonts. Now you can download TeX Equation in App Store, and create the most beautiful math equations in the world.