Aperture follows your system-wide preference for text smoothing (also known as "anti-aliasing"), so some smaller fonts may appear jagged on screen. Please note that this appearance only affects what you see on your computer screen; it does not affect the final printed version, which will be smoothed regardless of your text smoothing preferences.
The default setting in Mac OS X is not to smooth fonts that are 8 points in size or smaller because some very small fonts become more difficult to read when smoothed. To experiment and see what you like best, follow these steps:
You should now see small fonts smoothed in Aperture and most other applications.