In terms of the milkshake, that's the perfect icon. You actually share something when you stop having "a whole" and now you have "a part" but then someone else has "a part" as well. That's what I've seen parent teach their kids over and over again. Sharing the ball: we both use it, share your candy we both enjoy it, even if it means I'll have less.
With electronic articles and other media that gets shared, you actually share nothing in that sense, you just let someone know about it, whilst still keeping the whole yourself.
I know that semantically you can also "share information", and you lose nothing by doing it. But my point is that maybe most people associate sharing with "losing a bit to give to someone else" instead of just "letting know".
I am thinking hard and haven't come up with a better word, I admit it, but maybe there is actually a better word for describing that "electronic share" action?
The bullhorn looks promising, but like someone said, it looks like an axe is too small. And also someone else said it would have to be different enough from a volume icon.
Maybe two hands apart, one with a piece of "the whole" and the other hand with the other piece?
In that regard I liked the Android icon a lot, even though it's a bit too abstract. But it conveys the idea that you just multiplied the information, without losing anything yourself. Maybe a diagram of an "information bus" could work? like a straight horizontal line with a perpendicular line protuding from it, indicating that you keep going but still produced a new path/road/source?
Edit: added clarification