They also have DRKUSD on there, after they delisted it a few months ago. Could it be that they are getting more involved in other cryptocurrencies after seeing the insane volume that Ether has been getting?
They only seem to appear in the "Exchange Trading" section of the site. Under "Margin Trading" and "Margin Funding" ETH does NOT appear. But it does show in Exchange Trading, so that means something.
UPDATE: It was appearing on the beta site but Bitfinex has now removed it. I challenge anybody from Bitfinex to deny that these screenshots are real and that they put the ETHUSD and ETHBTC pairs on the beta site. The screenshots are 100% legit.
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More screenshots below: