Well, not anymore !
This little macroScript automatically selects the vertices that are symmetrical according to the local X axis of your mesh. You need to have selected vertices on the active Edit_Poly or Editable_Poly for it to work.
That can also be pretty useful when modeling a morph target !
If you want to change the symmetry axis to Y or Z, you'll have to change it in the code:
Look for this line:
Change this value to 2 or 3 for Y or Z axis, respectively.
symmetryAxis = 1
There is also a threshold value that you can edit if needed.
You can find the script here, and instructions on how to use them here !