My guess is that while that might help with the initial evaluation of the app, and possibly even smooth the initial sale (familiarity and all that), looking like other icons is a net negative for continued usage for your app.

I routinely try to check in with Foursquare on my phone and accidentally open Facebook, because their icons are similarly colored. Meanwhile, the "Words with Friends" icon is not something that could be easily confused with anything else, and I've never had a problem finding / using it.

Once your brand is established, those problems probably go away, but I know I've dropped a number of apps before because I wasn't using them because they were too difficult to easily identify in a menu lineup.