Sony is getting the idea of making its smartphones tougher, unlike many other companies. Unlike the old days where you could drop your Nokia 3310 and be assured it'll still work. Phones these days are lot more delicate because brittle components are used a lot more.
The Xperia Z and ZL are the new flagship devices coming from Sony. The Xperia Z is the big guy here, with the ZL being the cheaper alternative.
The Xperia Z is Sony's answer to the Galaxy S3 and the iPhone 5. It has a 1.5Ghz quad-core processor, 1080p 5-inch display, 4G/LTE capability, Android 4.1, 2GB of RAM, 13.1MP rear camera, NFC and is a mere 7.9mm thick. It has a huge 2330mAh battery and has 16GB of internal storage, you can also expand that with the available MicroSD card slot. What sets it apart from the others though is that it's water and dust resistant. Note that does not mean it's waterproof, just water resistant. So splashing water on it should be fine, but chucking it in a bath of water will still destroy it, unless you're quick to get it out.
The Xperia ZL has most of the same features as the Z but some minor differences. Instead of having a glass back, it uses rubbery matt finish. It isn't water and dust resistant either. But the insides are the same.
The two phones will be coming in the first quarter of 2013.