Therefore, the network FX are indirect because the utility of the network increases to advertisers through the increase in the number of common users.
There's no network FX for advertisers here.
Sure, the value to advertisers scales as the audience scales. But this differs from oldskool broadcast media how, exactly?
Advertisers don't benefit in the slightest from other advertisers using the ad-platform. Contrariwise, it just drives up the cost-per-eyeball - exactly the way it does in traditional media.
Yes, the connections between different Google "components" (as Scoble calls them) are valuable. But this has nothing to do with network effects.
I guess someone could argue that Google's readers benefit from there being more advertisers (more choice of informational links) and advertisers benefit from extra readers so there's a positive feedback going on there. But this is a kind of feedback that could exist in any media situation. It's not exclusive to Google and not what we normally mean by network effect.