I often travel with my Lenovo Thinkpad X200 Tablet and a few USB cables to power my peripherals (like my smarphone and iPod). So the "Always On USB" feature on my Thinkpad comes in very handy. I get to charge my devices at night by keeping them plugged in to my laptop. I can also charge them when I'm on the plan and when my laptop is in "sleep" mode.
If your laptop capable of "always on USB," it's a great feature when you're traveling.