Verified answer

There's a lone pair on the Cl atom, which makes the ion bent, or V-shaped. Therefore it's polar.

The ClO2^- ion is in fact an AX2E2 system with two lone pairs and is bent or V shaped.

The Cl-O δ-→ (and Cl-E:!) vectors do not cancel and hence the ion is polar.

http://en.wikipedia.org/wiki/Sodium_chlorite