Update 3rd October:
Released version is now here.

Requires Blender 2.43 or later.

This adds:
- support for 8.50 datarefs (thanks to Sandy)
- support for 8.50 “named lights”, “layer groups”, “ANIM_show/hide”, “ATTR_hard <surface>”
- importer creates armatures and bones for animations (unfortunately you have to manually parent the imported meshes to the appropriate bones).
- support for setting diffuse, emissive and specular attributes via Blender materials.
- support for controlling drawing order using Blender groups.
- support for slung_load_weight
- increased import and export resolution to 1/10th mm
- bugfixes for importing planes and weapons
- bugfixes for missing textures
- bugfix for exporting nested translations in animations
- X-Plane entries moved to bottom of Import and Export menus.

Please let me know if you have problems.

Go here to see the original:
Blender Import/export For 8.50