My memory arrived this evening. Installed easily, working perfectly!
Here you can see the new RAM showing up in About This Mac:
And here you can see (most of ) its presence in Activity Monitor:
As expected, I’m only able to use 3 of the 4 GB installed, due to mapping limitations in Intel’s chipsets. But I’m okay with that. I still get to use more than the official limit of 2GB without sacrificing video speed.