Page 130 of SR4a says "Cumulative positive Social Modifiers may not exceed the character’s combined natural Attribute + Skill Ratings."

Now I see two possible interpretations of this, I wonder which is correct:

• The sentence is next to the social modifiers table, and it refers to the bonus's from the table
• The value of all social modifiers from things like glamour, tailored pheromenes, kinesics, and modifiers from the table

The second would be valid, as far as I can imagine.
Also note that is about the cumulative total, so any 'redundant' positive mods will still offset negative ones.

It's Social Modifiers, not modifiers for social skill tests. It's restricting modifiers depending on the social circumstances and not modifiers modifying one's social abilities.
So I go for everything from the table plus things like Freak modifiers from RC and maybe some more stuff I don't remember right now.

Exactly. So cosmetic biomods would fall under that category (because they essentially give you the "romantically attractive to the NPC" modifier), but things like kinesics or tailored pheromones would not.

It would be different if it had said positive dice pool modifiers.

Yeap, the first option is the correct one.