I have blogged previously about how the tools included within the Android SDK provide a very useful means of capturing screenshots from a connected Android device and also transferring files to and from devices, but the DDMS tool does not launch successfully on the new Snow Leopard operating system.

The fix is relatively simple, but not immediately obvious. I worked out the first bit myself, but thanks to Buffawhat for the second bit (http://buffawhat.com/2783/android-sdk-ddms-broken-in-snow-leopard-lets-f...)

Within the Java Preferences panel you will need to set the default Java virtual machine from 64-bit to 32-bit.
Open the Applications folder, and then browse to Utilities --> Java Preferences, the following window will be displayed:

Set the 32-bit VM to be the default simply by dragging it above the entry for the 64-bit VM.
Close the window to apply changes.

You will then need to make a small edit of the DDMS script file itself. Browse to where you have extracted the SDK file and open the DDMS file in the Tools folder in a suitable text editor.
Locate the section beginning:

# Mac OS X needs an additional arg, or you get an "illegal thread"
complaint.
if [ `uname` = "Darwin" ]; then
    os_opts="-XstartOnFirstThread"

And add the text -d32 as shown below:

Now DDMS will launch successfully.