We list below reports on who has not been invited. From these it appears that they include Bishop Gene Robinson of New Hampshire and the bishops from CANA (Martyn Minns) and AMiA. Bishop Robinson may be invited as a guest.
Robert Barr (Associated Press) in The Washington Post 2 Bishops Not Invited to Anglican Parley [This article has been published on many other sites but this appears to be the earliest.]
Update that Washington Post page now contains a later AP story by Rachel Zoll Gay Bishop Kept Out of Anglican Meeting. The earlier Robert Barr story can be found here.
Reuters Luke Baker Gay bishop snubbed by Anglican conference
Ruth Gledhill in The Times Gay bishop not invited to Lambeth conference
Natalie Paris and agencies in The Telegraph Gay bishop’s church conference snub
BBC Gay row US Anglicans miss summit
Bishop Robinson has responded to his non-invitation here.
The Living Church has more detail on other exclusions at No Lambeth Invitation for Bishop Robinson by George Conger.