Google already makes extensive use of the Wine library to have Picasa run under Linux. According to the Google Open Source Blog, Google has hired Codeweaver to enhance Wine so that it can run Adobe Photoshop CS & CS2 under Linux.
According to the Wine wiki, CS2 works pretty well, with the usual glitches and tweaks necessary. For owners of a Photoshop license, that could be a nice stop-gap, until a proper open-source solution can be found.
Edit: APCMag.com also has a more fleshy article on the subject.