In the current orca they can reply or post a topic and choose the little "tree" icon next to the "anchor" which will allow them to add an image from a location anywhere on the internet if they fill it out. It's a little confusing to the new user, but the more internet savy user is probably used to it. It won't upload to your server or host but link to it and display it in the forum.

There is a plugin for the editors that dolphin 6.0/6.1x uses to upload a file and display it. It's not a boonex or dolphin thing it is a 3rd party plugin for the tiny_mce editor that dolphin uses. It works but not that user friendly to your users without a major code editing.

I think boonex is working on this feature for the new dolphin 7 release so we will have to keep our fingers crossed on it.