IPhoto, Aperture Plug-ins Let You Tweet Photos
Twitter may some day get baked into the very fabric of Mac OS X, allowing you to tweet from Safari, Mail, or even the Finder. If you want to easily tweet photos from iPhoto or Aperture in the meantime, though, Blue Crowbar Software has a couple of plugins for you.
Both plugins have demo versions available, but they embed a watermark and are limited to posting at 500 x 500 pixel dimensions. They also require Mac OS X 10.5 Leopard and are Universal. iPhoto2Twitter requires iPhoto '08 or '09, while Aperture2Twitter requires Aperture 2.