Currently Being ModeratedDec 10, 2012 6:21 AM (in response to andmixg)
There has never been an "upload to iCloud" option. There is an "add to icloud" option, though. This option will be in the contextual menu (AKA the right-click menu) when a track has not yet been processed by iTunes Match on your computer.
Generally speaking though this should not be necessary as any new music added to the iTunes library will kick off a scan and match process in which the files with either be matched or uploaded.