The previously long-stable version (3.6.1-r4) was broken due to incompatibility with libjpeg > 6b (and 6b is not marked stable).
Version 3.7.0_rc3 has been the latest version for a very long time, so even though it is marked as an RC by upstream, I believe it should be marked stable at this point. We can wait 30 days and mark the fixed 3.6.1-r5 stable as well, but it would be good to have a working stable version in the tree now.
A fix for 3.6.1-r4 is known and now being verified, but it will be ~arch and not stabilized immediately since it requires rebuilding.
To test 3.7.0_rc3, please just emerge it with FEATURES="test". You should see a small image appear momentarily, and the test should pass.
emerges, passes the test phase
Stable for HPPA.
Blocking libpng 1.5 stabilization wrt bug #387465.