Eclipse 3.3 changed this behavior and I was just living without it until I found a series of blog entries (referenced at the end) that held the answer to my problem. Eclipse 3.3 changed the default setting for those hot keys and clicking the respective buttons on the tool bar for launches. To get the pre-3.3 functionality back, all I had to do was go to Window -> Preferences on the menu, and then into the "type filter text" input box, type "Launching". If you select the item under the Run/Debug category, you'll see a dialog that will let you set up the launch function to your liking. I personally prefer the Launch Operation section to have the Launch the select resource or active editor... radio checked, and under that radio I also check the Launch the previously launched application radio.
This way I can speed up the debug/test cycle and remove the need for the mouse! There are lots of other gems in the blog entries I found, so have a look at those.