The lights are on
UPDATE (2/15): I've heard from several people via email and Twitter that they've tested this on units that do not allow the cable to be plugged in the wrong way. The people reporting this have mostly been electronics store employees. While we can confirm that our office units can be plugged in either way, this may be because they are not final retail builds. We'll test this on retail units after launch day.
UPDATE (2/23): I just bought my personal Vita today, and I can confirm that it is not an issue. The cable can't plug in the wrong way.
As we've been reviewing Vita games for the last month or so, several of us have noticed an odd design decision when it comes to the portable's charging cable. You see, most devices only allow their charging cable to plug in one way...the way it's supposed to work. Try plugging in your iPad or 3DS with the cable facing the wrong way, and you won't get very far. The Vita, on the other hand, lets you snugly insert the charging cable either way.
I learned this as I was reviewing Wipeout 2048. The battery level was in the red, so I plugged the system in. Considering it clicked into place just fine, I figured I was set to play as long as I wanted. Unfortunately, the system shut down mid-race and I lost my progress. It wouldn't turn on again, even though the system was plugged in. I texted Kyle, and it seems he ran into the same problem.
We discovered that even though the cable fits either way, it will only charge if it's plugged in as seen above (with the PS logo facing up). You can confirm that the system is charging if an animation of electric currents is running through the onscreen battery indicator.
It's a pretty dumb design decision, and one that Vita owners will surely become aware of shortly after their purchase. We just wanted to get the tip out there so you don't lose even one save before you figure this out.