Yes thats called the Multi mode (rmb + sw marking menu item), again a feature in maya 2009, 2010, 2011. After that the complete object is hot untill you decide later that object selection is what you need instead foa purely modelling mode.
In any case you can not really use a plugin to do this because you woudl actually need the very raw selection buffer data, and unless you want to implement the entire maya gui anew you couldnt do it easily.
I bet the next question is going to be how to implement drag painting selection? Or how to go into projection mode.