WIFI Adapter:
Manufacture: ELEMENT14
Model: WIPI
Newark part number: 07W8938
Data Sheet

Got the WI PI  adapter from Newark / Eleement14.
Works as is with the Raspbian "wheezy" version 6.0 + image.  The instructions state that this adapter will not work with any other image. The latest image is pre-configured and works native without modifications so just ignore the configurations instruction sheet that came with the adapter. If your image has the WIFI configuration utility on the desktop then you are good to go. If you have an older image without and you don't want to change images, then you will have to do the manual configuration per the instruction sheet.

Note I was having power problems trying to use the WI PI and VGA adapter at the same time. Screen would blank out every few seconds  and the WI PI would not work.
On the older RPi boards there are 2 fuses, one for each of the USB ports. Fuse F1 and F2 rated 400mA each. The newer rev 2.0 RPi boards do not have these fuses at all. I shorted out these fuses by soldering a jumper wire across them. If you are not comfortable with that then you will have to use a powered USB hub.