An employee of the bank serves in the capacity of teller and CSR. What are the risks or prohibitions (or even considerations) for letting the same employee also work in the trust department? Are there any segregation of duties issues to consider, or anything that would prevent the employee from also working in the trust department of a community bank, from an access standpoint or otherwise?

Not if the Trust Department is part of the bank.

Agree with Randy (of course)

The major consideration is the dual control for transactions - they cannot create a transfer and process it themself.

Playing off the scenario above (and after reading the FDIC updates to Part 328) - what considerations should be made if that person uses the same "desk" for teller, CSR, and trust duties?

What are others doing in situations such as this from a segregation of deposit and non-deposit areas?

You are going to have to define "trust duties". What are they doing for the trust department if they are not a trained and dedicated trust officer? Seems like a strange overlap for a teller to be acting in a manner of a trust officer.