Relevant to Blender v2.31
To move groups of objects, press GKEY to activate Grab mode for all selected objects. The selected objects will be displayed as white wireframes and can be moved with the mouse (without pressing any mouse buttons). To confirm the new position, click LMB or press ENTER; to cancel Grab mode, click RMB or press ESC. The header of the 3D Window displays the distance you are moving.
To lock movement to an axis of the global coordinate system, enter Grab mode, move the object roughly along the desired axis, then press MMB. To deactivate locking press MMB again. As a new 2.3 feature you can constrain movement to a given axis by pressing XKEY, YKEY or ZKEY. A single key constrains movement to the corresponding global axis, as MMB does. A second keypress of the same key constrains movement to the corresponding Object local axis. A third keypress of the same key removes constraints. Lines are drawn to let you better visualize the constraint.
Once grabbing is activated you can enter the Object translation numerically by simply typing in a number. This will let you enter the first co-ordinate shown in the 3D Window header. You can change co-ordinate with TAB use NKEY to exit/re-start numeric input mode, ENTER to finalize and ESC to exit. BACKSPACE will return to original values. Please note that you must use the keyboard .KEY not the NUM. for decimals.
If you keep CTRL pressed while moving the object you will activate snap mode, and the object will move by a whole number of Blender units (grid squares). Snap mode ends when you release CTRL so be sure to confirm the position before releasing it.
The location of selected objects can be reset to the default value by pressing ALT-G.
If you are striving for very fine and precise positioning, keep SHIFT pressed as you move. This way a large mouse movement will translate to a small object movement, which allows for fine tuning.
You can also enter Grab mode by drawing a straight line while holding down LMB.