Yes, the #"Mg"^(2+)# ion and the neutral neon atom are isoelectronic, which implies that they have the same number of electrons and, of course, the same electron configuration.
Magnesium has an atomic number of 12, which means its neutral atom has 12 electrons. The #"Mg"^(2+)# ion is formed when the neutral magnesium atom loses 2 electrons, which brings its total number of electrons to 10.
Neon, which has an atomic number of 10, also has 10 electrons, which is why the electron configurations for the #"Mg"^(2+)# and for the neutral #"Ne"# atom will be the same.
#"Ne":1s^(2)2s^(2)2p^(6)#
#"Mg"^(2+): 1s^(2)2s^(2)2p^(6)#
Using the noble gas shorthand notation will get
#"Mg": [Ne]3s^(2)#
#"Mg"^(2+): [Ne]#
For example, #"Mg"^(2+)# is isoelectronic with other ions as well, like #"O"^(2-)#, #"Na"^(+)#, and #"Al"^(3+)#, just to name a few.
More on the #"Mg"^(2+)# ion here:
http://socratic.org/questions/what-is-the-full-electron-configuration-for-mg2
