The plug-in is a wrapper around open-exr (http://www.openexr.com) that consists of two projects, ilmbase-1.0.1 and openexr-1.6.1.
I have only tested it on windows XP 32 machine. So there might be some work making it work on other platforms.
The plug-in supports writing and reading EXR files. When writing it can use the data type GL_HALF_FLOAT_ARB(se ilmbase-1.0.1) and GL_FLOAT. When reading the data type always becomes GL_HALF_FLOAT_ARB. It supports textures with three and four channels.
When reading an exr file it automatically removes Alfa channel if it didn't store any information."
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From Robert Osfield, started work on ported it to other platforms, but could fix some problems relating to error:
?Imf::OStream::OStream(const Imf::OStream&)? is private
I'm checking in now so that others can have a bash at completing the port.