I want to burn a .img file of Wheezy OS to my 8GB SD Card from Mac OS X but can't figure out how.

Any help would be appreciated.
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First, verify the path to your SD card. You can do this by running the following command from terminal: 

`diskutil list`

The output shows a list of disks currently mounted on the system. Here's the relevant line from my output: 

```
/dev/disk3
#:                       TYPE NAME                    SIZE       IDENTIFIER
0:     FDisk_partition_scheme                        *8.0 GB     disk3
1:                 DOS_FAT_32 RPISDCARD               8.0 GB     disk3s1

```

In this case I can verify `/dev/disk3` is my SD card because the TYPE, NAME and SIZE values are correct. 

If you have an existing partition on the disk you may need to unmount it, otherwise you'll get a "Resource busy" error message when you try to write the image. 

```
diskutil unmount /dev/disk3s1

```

Now to write the image file to the disk. Note the 'r' added to `rdisk3` which drastically improves write performance by telling `dd` to operate in raw disk mode:

```
sudo dd if=RetroPieImage_ver2.3.img of=/dev/rdisk3 bs=1m

```

Depending on the size of your SDcard this may take a while. You can press `CTRL+T` to see the current status of `dd`. As an example for my Samsung 8GB SD card the write speed was 12MB/s the command took 11mins to complete.
I made a script to burn .img or .iso files to SD card or USB. 

[Github > burn.sh](https://github.com/jmcerrejon/scripts/blob/master/burn.sh)