The other question is about "auto mount" features. My question was specifically about the ability to mount a drive that I ejected myself in the same session, via GUI.
This can be done in the Disks program, as Mitch pointed out in the comments:
- Click on the drive, and look for the little square icon below the graph with the partitions.
- When the device is mounted, clicking this icon will unmount the drive ("stop").
- When the device is not mounted, the icon will show a "play" arrow instead (similar to a music player). Clicking the "play" button will mount the drive.
I feel this question is relevant, because in Windows 7 I never found a way to do this. If I ejected my (very noisy) Seagate USB hardrive, I would be unable to mount it again short of restarting Windows or pulling and plugging the cable again.