[sbf501]

I was told by a friend who has ~$30k of ether sitting in there either as ether or GUSD, I don't know which, we haven't talked about it since the crash for obvious reasons.

It is on their website, but you have enlightened me: it won't protect them from grubby Winklevoss shenanigans, only the failure of the bank, and apparently only for USD assets. From the website:

U.S. DOLLARS

U.S. dollars in your Gemini Account may be held at Silvergate Bank, State Street Bank and Trust Company, JPMorgan Chase Bank, N.A. or Signature Bank and thus may be eligible for FDIC “pass-through” insurance, subject to applicable limitations. Please see the FDIC Insurance section of our User Agreement for more information.

EDIT: Oh, my copy-paste is from the very link you sent. Doh.