Michael Kubler has posted some code regarding the image caption feature that has been in WordPress since 2.6.

A little while ago I noticed that wordpress 2.6 introduced the ability to add captions to images. This seemed like a great idea, and looked great in the actual Wordpress Admin WYSIWYG editor (TinyMCE), however I couldn’t actually find any themes that had the proper CSS for the captioning, so decided I would make it up myself.

He has provided CSS code you can simply paste directly into your styelsheet. Most will be able to use this tweak right out of the box. Fantastic work Michael. We look forward to seeing more good work like this from you.