How did Saruman know who Gimli was ?

[CSteefel]

I don't recall any mention of Gimli in the Hobbit, so how would Gloin's son have come to Saruman's attention through the business of Smaug. I also don't see what it would have to do with visits to Rivendell, since the visit of Gimli here also appeared to be a first for him.

There is a slight chance he knew of Gloin's name (although still unlikely that he would have focused on one of this large party of dwarves), but I don't see how this gets him the name of Gimli and that Gimli is Gloin's son...