I am right now testing Krita Beta 3.0 (git 962 bfe1) and I can not open or save PNG files. They seems to be excluded from Krita. Is that so?

That was a little mixup in our file editing system. We'll be releasing a new build tomorrow or the day after, which should have this fixed.

I received an error - bug 104959 when I tried to open a PNG file, the problem is with the .desktop files for the krita import/export filter which has been fixed in cvs.

The latest builds, which are available from the download page now (scroll down to the bleeding edge section) should have the png filter fixes.