Adobe and Microsoft just posted a notice on the OpenType mailing list about a draft of version 1.5 of the OpenType spec, and requesting suggestions/proposals for version 1.6.

If you're interested in the mailing list:
subscribe: opentype-migration-sub@indx.co.uk

More details on my blog here: http://blogs.adobe.com/typblography/2008/01/opentype_15_draft.html

Cheers,

T