Sometimes it's more about execution than product inventory.

If you go to http://pixlr.com/app, you immediately get a Photoshop interface.

If you go to http://www.picnik.com/app, you get to wait for a minute while the app 'fluffs clouds' and then you get a screen full of buttons and text ... when do I get to edit my photo again?

I had never heard of splashup.com. Their app execution seems good compared to picnik, comparable to pixlr. Perhaps marketing failed?

Nah, it is always about execution :)

It may not be a unique idea but it's certainly the best execution when it comes to familiarity. Not only does Pixlr look and feel like Photoshop, but it supports Photoshop keyboard shortcuts, while the other two apps do not. As an experienced Photoshop user, my efficiency with the tool depends solely on those shortcuts.