R"n Toby Katz quoted RDM:
> AFAIK, the only need for a minyan is for bentching. I
> don't think the Nodeh L'shimcha is sid without one.

Actually, Nodeh L'Shimcha *is* said when Sheva Brachos are omitted 
(either for lack of Panim Chadashos, or for lack of a minyan, 
provided there's at least a mezuman). Maybe he was thinking of 
Shehasimcha Bim'ono?

R' Avrohom Dubin (or was it Gershon writing from someone else's email 
account?) wrote:
> The Panim Chadoshos of Shabbos is not the Shabbos
> itself. Rather the people attending the Sheva Brochos
> have a different Panim than they had on Thursday night.

If that were the case, then the people who came for dinner on Friday 
night would not count for Shabbos lunch, because they have the same 
panim as the night before. You'd need someone who is either totally 
new, or had been at a meal other than the Friday night meal. But I 
think the halacha does allow using the exact same people for lunch as 
on the previous evening.

Akiva Miller