I know that at one point last year, Honda admitted that they are getting some sort of consultancy, but to my knowledge, it was never really confirmed who it was getting it from.
Additionally, if Ilmor is really giving Honda consultancy, wouldn't that be strange, considering that the Chevrolet engines for IndyCar is mainly an Ilmor engine? Now I know it's a totally different technology, but I still have my questions.
Some people seem also to be of the impression that with such consultancy, the entire team will change. Well that's not the case. Consultancy does give insights to technologies and information which would otherwise take months to develop, however, at the end of the day, all development is still done by Honda to apply and test such concepts within their own designs.