With the new VB3 conditionals, this is cake. First, create a new User Profile Field.. use Single-Selection Radio Buttons. Make two options, "on" and "off". Make note of the profilefieldid.
Then, in whichever template you call the sidepanel and encompass it with:
HTML Code:
<if condition="$bbuserinfo['fieldXX']==On">
$SIDEPANELVAR
</if>
Of course, replace the XX with the profilefieldid. This isn't tested, but it should work fine.