Indeed, apps have the option for recurring toast notifications. I have noticed Tweetro notifies me (e.g. a direct message) every 5 minutes or so if I choose not to pay attention (or in the cases mentioned above, if you miss it for whatever reason). By the way, the app does not need to be running for the live tile / notifications to be updated, which makes it all the more effective. For that matter, it keeps updating even if your system is in standby! (OS X ML does have something similar called Power Nap, but not sure if it works well) E.g. in the above case, Tweetro sends up the notification even though I haven't opened it at all since the last reboot. That said, the alpha apps in RP don't seem to work flawlessly, some don't even support notifications yet and some don't update live tiles / notifications correctly, but pretty sure these teething issues will be solved GA time, if not RTM.
iOS used to have the recurrent notification and it was annoying as hell.
also, i blame apple for giving it the name of "notification center".
my guess is windows will eventually implement something similar. the tiles are only useful for notifications if you arrange them properly and check them every now and them. but a tile is NOT a notification. just because its updated doesnt mean u noticed. especially if all other tiles are doing the same.
The pulldown notification in Both android and iOS is pretty damnhorrible as far as overview go and there's far less organization and far more scrolling on those than on the start screen on WP or W8.
with all the crap putting notifications in those thigns on my iOS and Android devices, sorting out what are important notifications Ic are about is a nightmare. whereas on WP and Win8 I just put the important tiles on top and I see what's important and has news for me. and with WP each mail account also gets ot's own icon on the lock screen so I can see which account has new mail for me, important account or mostly trash account, or pretty much only trash account.
I'm sorry but an drop down notification sorry is a horrible solution and as far from the holy notification grail you can come.
android (and i believe iOS too) lets you choose whichs apps should never be allowed to trigger a notification, but most apps DO have a way of customizing the notifications. if you're so bothered with 'meaningless' notification (ive noticed them on both OSs), then you can hand-pick which to disable pretty easily (especially in jellybean). but i dont see how this is any different than coming up with a custom arrangement of your live tiles.