I used the Instagram Lo-Fi filter a lot and wonder how I can reproduce the effect in Photoshop...
You will find lots of Instagram filters as Photoshop Action, created by Daniel Box. They are good and really useful :)
This looks to me like just a contrast boost and slight desaturation. Try duplicating the background layer, setting the Layer Mode to Overlay, then using a Hue/Saturation adjustment layer, drop the saturation a little.
If this produces blown highlights, you can either lower the opacity of the Overlay layer, or instead use a Levels adjustment and bring the left-most (black) point in to the centre more.