Google Docs introduced a great collaborative feature today, the ability to protect individual worksheets (aka sheets) in a spreadsheet . All you have to do to protect a sheet is click on the sheet button, select Protect sheet and then set the editing features.
I'm sure this will be useful for many users and I will be definitely using it for the labs that I teach. There are 10 Teaching Assistants for these labs and now I can control which sheets they can enter marks for. Awesome feature.
Control Who You Want To Edit Worksheets