Currently, you can rotate photos on Flickr, but the editing stops there. When the new tools launch, users will be able to edit photos more extensively using the Picnik Flash based tools (see our review here).
The deal has been signed and implementation will occur sometime in the next few months, Flickr told me yesterday. Users will be presented with an edit option on the photo page. Clicking it takes the user to a new Flickr photo edit page, with the Picnik tools integrated via an iframe. After editing, users can add the edited photo to their Flickr account or, if they are a Flickr pro user, overwrite the original.
Business terms around the deal are not being disclosed at this time. Picnik is self funded to date.