For me it can happen in portrait mode.
Also, where's the time, signal strength, battery, in safari???
It cuts off only the address bar, time, signal strength and battery are all in the status bar, which should stay up there regardless of what app you're in, unless you're playing a game, or watching a video.
The bar with time and battery is gone...
What to do?
Take a screenshot for us, and upload it here. Power Button + Home button at the same time.
You can even upload it using the iPhone itself, as iOS 6 supports picture uploading to websites
I took a screen shot few minutes ago, but how do I upload it from the iPhone?
Make sure you're on the desktop version of MacRumors, then attach it using the "manage attachments" button below the box where you type in the reply.
In that picture it looks like I used photoshop.
It's just a black bar above what you see in the pic.
Go to the iPhone home screen, and open up the multi-tasking tray, and close out of Safari, and reopen it, does it still do this?