Sorry, but that was the best I could think of for a title to describe a new experience for me, that I think has not been covered here yet.

Selected Uber X, non-shared ride for $8. Almost immediately, I was asked whether I wanted to share a ride with an existing passenger going to the "same" destination. Sounded interesting, so I said yes.

Car appeared very quickly, we proceeded directly to my destination where I was dropped off at the door; they must have meant the same neighborhood, not exact same spot, as the other passenger was obviously continuing on somewhere else. I was rather annoyed to see that they charged me the full $8, no shared discount at all. However, I noticed just now that they apparently deposited $3 Uber Cash in my account from saying yes. Not a bad return!

Uber is trying a X-Shared rides.

Yes, as noted by arollins this is something uber rolled out in select cities about a month ago. Here is the info:
https://www.uber.com/newsroom/nonstop-shared-rides/