[quote name='kromekoran']Gears of War (player matches) is all I know of first hand.[/QUOTE]
No.
GoW doesn't allow Guests. Guests are like Halo 2 and Ghost Recon 2 style.
In GoW both players need to have Gold Accounts.
[quote name='fraggedbylaggers']When you guys mean guests do you mean one person with a gold profile and the other(s) with silver (a la Halo 2) or do you mean that the guest needs gold too? I am pretty sure both accounts need to be gold for GOW...[/QUOTE]
You're wrong too. Halo 2 didn't use silver accounts. In Halo 2 both players would play under the same account, but one would just have a number tacked on the end of his name, and a "guest" logo.
I think PDZ had guests.
It looks like Microsoft's website contradicts my information.
GUESTS on 360
[quote name='MS']Guests with Xbox 360
The guest feature for Xbox Live® lets your buddy join in the Xbox Live multiplayer action on your console before he or she becomes an Xbox Live member. All you need is an extra Xbox 360 controller, either wired or wireless.
Two people can play side-by-side on Xbox Live from a single console when a game supports the following:
Xbox Live play
Multiplayer gaming
Split-screen display
When you fire up a game, select your gamertag to register yourself and have your friend select Guest.
You, of course, have to be a member of Xbox Live.[/quote]
Hmmmm... very weird. I will have to try this out.