[dserban]

"Once open-source gets good enough, you'd be crazy to compete with it." -Larry Ellison

Any startup that sets out to recreate Photoshop would also compete with GIMP and Pixelmator.

[nailer]

Pixelmator's proprietary, and can't run on non OS X ATM due to reliance on, IIRC, CoreGraphics or similar. If they recreated those libraries on other platforms they may have a PS competitor.

GIMP is poor quality.