The only workaround I am aware of is using applescript in Spark/FastScripts with
do shell script "python script.py"
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In 10.6 Snow Leopard it's quite easy to add any command to the Services menu of each application (or specific applications), and then assign a keyboard shortcut.
Here on Super User, see Fast User Switching/Apple Menu? for an example that invokes some shell script.
Other applications that launch AppleScripts like FastScripts (lite) include Quicksilver, Butler, and ControllerMate.
I believe Quicksilver may allow for the execution of Shell scripts directly from within the application, but I dislike Quicksilver on the point that it seems to flake out more often than Butler does.