Yeah its free. I wrote it!!! :attn:

Find it in the Indigo Unbiased Renderer thread in the Member's lounge. ITs just a mass of script. Copy-paste it into your script editor, then copy-paste the output into an XML file. And don't worry if it's slow, MEL itself is very slow. Maya doesn't crash if it just goes white and stops responding. It's still working. Best is to just leave it alone.

Anyway- you can also find the same thing in the MEL scripts and Programmiong forum- Maya->Indigo exporter script.

But, as of now, you need to do a little hand-tweaking of the XML file to add stuff like sun, HDR environment (and so far only EXR's indigo doesn't support HDR). And you need to run my script on Indigo 0.5.3 or higher.

Later,
Matt