Of course, have a look here for example:
www.themepartner.com/blog/71/joomla-25-new-features-made-visual-screenshots/ (scroll down), or here:
community.joomla.org/blogs/community/1533-new-features-in-joomla-25.html.
You have to enable this feature first by going to article manager-options-and then second tab editing layout and enable it:
www.ostraining.com/blog/joomla/joomla25/, point 11.
Now that is all fine but only yet supported by beez. I have tried (a bit) to get sexy lightbox working on that field, but no luck so far.
The second relevant change for lightboxes/thumbnails is this:
github.com/joomla/joomla-platform/pull/427. That is beyond me:), but i do understand that there is finally a joomla out of the box way to generate thumbs. The less you have to add the better, so i am guessing that you could use that class to generate thumbs for all your extensions.
I think that with the image field and the possibility of generating thumbs natively in j2.5 editing an article could become a lot easier for users, a bit like with a cck, without having to resort and rely on any cck and just sticking to com_content.
Sorry, is a short a possible:)