http://www.fudzilla.com/content/view/17720/1/

We learned that some of AMD loyal press (not us) got samples of a card codenamed Trillian. Ever since the HD 5870 paper launch in Oakland, when we had a bit of an argument with ATI's PR chap, we never received any sample for them since we don't do what they want us to do. Well, that is called free press and I guess that we're willing to pay the price for it.

Anyway, Trillian is a tuned HD 5870 card with slightly higher performance. Last year AMD boosted HD 4870 specifications with the HD 4890 1GHz card, and this is exactly what we expect this time around.

We don’t know if AMD plans to use the HD 5890 brand, but we would not be surprised if they do but what we are quite sure is that Trillian won’t be enough.

The smart part of AMD knows that but they still have to play the game that Geforce GTX 480 is bad, evil and broken as they know that Nvidia should be able to challenge them, well once it finally launches Geforce GTX 480.
Why wouldn't they use the 5890 name... Its in the same vain as 4890 to the 4870.