Since 0.5.2 alpha, I've been right through the code and changed it all to be compatible with object-oriented plugins. That was a pretty hefty task and is the reason for the delay in making Hotaru 0.6 available.
Things are starting to look a little more solid now and we're getting ready to let you try it. I've updated all the documentation in these forums to reflect the changes in Hotaru 0.6 and would like to do just a little more testing on the SVN 0.6 branch before moving the new code to the trunk. Once that's done, I'll upload it to the demo site for some final live testing before releasing it as a .zip download at the start of October. If you'd like to help out with testing, that would be greatly appreciated.
When we get into October, we can start extending Hotaru with more features.