In a message dated 11/1/2003 6:07:56 PM Eastern Standard Time,
[log in to unmask] writes:

>The subjunctive is introducing a relative clause in your sentence:
>        I wish
 >           (that) he would stop talking.

Although that's plainly some kind of subordinate clause, I don't think it's
strictly speaking a relative clause.

"That" here is usually considered a subordinating conjunction, unlike in "I
need a sweater that will keep me warm," where "that" is a relative pronoun.