Wifi download speed issues

I just did a speed check on my macbook and iphone4 using the speedtest.net website and app.

On my Macbook I'm getting 16mb/s download and 4mb/s upload
On my iPhone4 I'm getting 0.6mb/s download and 3.8mb/s upload

Both are connected to the same wifi

I cannot fathom why my iPhone is only getting 0.6mb/s through the wifi. It's slower than the 3g signal