it means: "to play a musical instrument in an informal way without playing a particular piece of music" or "to think about something in a way that is not very serious" - i rather like it :)
@kali66@maree_sanderson i've updated the description with the definition... i think it's rather perfect... i seem to "noodle" a lot (using the 2nd definition and other than when i am at work where i noodle not at all ;p)