This would be nice to insert into a waterhouse-slot, rather than making a whole lot of tabs that inevitably get lost.
Given that it's LCD technology (or even if it's not, whatever it is), changing the colour and/or density of the centre-hole would be nice too, that Apo-Ronar of mine doesn't easily take coloured filters...

I've seen a Canon patent for this type of thing in 135-sized lenses too, so it's not just limited to phones.