Canada-based Solestrom has developed a bikini with a built-in dosimeter that's sensitive to sunlight. It will warn you when your cumulative exposure (over the course of a day) becomes dangerously high, and if you have the good sense God gave Gruyere, you'll head for the shade when it tells you to.
I'm a bit concerned about this. There are bars where people compete to see who can pop the dial on a breathalyzer (give people a metric and they'll try to maximize it)--this bikini might actually encourage similarly perverse behavior on the beaches. ("Hey, everyone! Let's play Dosimiter Chicken!") But leave that aside. The point here is that devices are once again trying to make their way into our clothing. The most interesting example I've heard about to date (embarrassingly, I can't find the reference) is an MP3-bikini whose speakers are built into the top. This is the truth.
At first blush, textiles seem like a hostile environment for electronics, but it turns out that marrying the two is perfectly feasible. But why bother? My smartphone is, I'd argue, already a wearable device, and there's no advantage to weaving it into my undershirt (particularly if I then have to wear the same undershirt day after day). And my phone is far from "full" -- although it's got a plethora of features and functions, many more (biomedical monitoring, biometric authentication, expandable screen, personal security, gesture-based input, life logging, monocular and, what the heck, dosimeter) are still possible and will "fit" perfectly well. Some might require new peripherals, but the odds are they'd be added to existing non-clothing platforms (headset, watch, ring, filling) or simply implanted in your abdomen. Don't misunderstand me: I'm not against wearable electronics. I just think they're already here.