"Seek and ye shall find" actually works!  The very same problem (where the 'Export object...' option is always greyed-out) has been bugging me for ages, so I finally got around to finding out why... and Svarg had already just asked the same question! 

I think that option is very poorly named - I tried everything to select an object, but nothing worked of course. However, all I wanted to do was re-use an object I'd created in another scene, so I followed  Mahray's idea of just saving out the object into the  create palette - perfect!! That was just what I was after! Many, many thanks !!

(ps this is my first post  to Renderosity!) :)