It's only available from the Japanese Amazon store right now, but Scentee is a hardware dongle for your iPhone that will allow scent-based communication. You load it up with a cartridge containing your favorite scent and then configure various app triggers to let the smell loose at appropriate times. Bundled apps include olfactory notifications when someone likes one of your Facebook posts, timers and alarm clocks.
There also a 10-minute video on the site that seems to be more like a b-grade soap opera than an ad for the product. Go figure.