In Query Analyzer, we could easily comment blocks of code using Ctrl+Shift+C and uncomment blocks of code using Ctrl+Shift+R.
These keyboard shortcuts do not work in Management Studio unless you switch the keyboard scheme to SQL Server 2000.
In Management Studio, you can comment blocks of code using Ctrl+K, Ctrl+C and uncomment blocks of code using Ctrl+K, Ctrl+U. These are the same keyboard shortcuts that you would use to comment blocks of code in Visual Studio .NET, so I'm sure that's why Microsoft decided to switch the shortcuts.
To see other keyboard shortcuts for T-SQL code in Management Studio, open a query window by clicking the New Query button. Click on the Edit menu then Advanced. You must be in a query window for the Advanced item to appear in the Edit menu.