This is simply genius. Since smartphone cameras don't have lens mounts, attaching a macro or zoom lens usually requires a cumbersome case. But by embedding one in an elastic band, this macro lens can easily be used on any smartphone.
If I had to nitpick I'd point out that the Macro Cell Lens Band does end up covering the iPhone 4's flash, but I never use it for anything other than as a flashlight anyways, so I'm ok with that. And since the band can be used on any smartphone, that may not actually be an issue for other users.
For just £10 it's the cheapest and easiest way to add macro capabilities to your phone, and here's to hoping they've got a wide angle and zoom version in the works, or a single band that includes all three. [Photojojo]