I'm aware of that. It will be hard to catch up though. I use GIMP for a few things, and it has about the full functionality of PS 4.0, plus a few unusual capabilities if you download the plugins for animation. But with no smart objects, no adjustment layers, and no 3D, it's going to be a long haul to achieve PS CS3 XT equivalency. Krita has adjustment layers, but seemed to have other issues last time I checked...and I can't forever be checking to see if anyone has "caught up." It's always a catch-up game with Open-Source, and with few exceptions (at least in my areas of interest, mainly graphics) there's very little that's truly innovative.
That's not always bad, of course. It could be argued that even the GNOME desktop (which is what non-coders really find so compelling about Ubuntu, and often mistake forLinux) in so many of these OS is functionally equivalent to the old, no-frills pre-OS-X Apple desktop. KDE has attempted some innovation, on the other hand, but I'm not sure anyone really wants more elaborate desktop managers. Do we really need things like Compiz to be productive, anyway?
What actually led me to investigate the whole topic of SU on Linux was the complexity and increasing productivity-restriction of the two main commercial OS, Mac and Vista/Windows 7. I want a bolt-hole when Windows XP finally becomes unusable on modern hardware...open-source versus commercial software development is utterly irrelevant in my particular circumstances.