Philips still makes those kinds of clocks. The "light up slowly" comes from LEDs, now, and the color of the light ramps up from red, through orange, eventually to white, over the course of a (user-configurable) timespan. They're pretty expensive for an alarm clock. I have one (it was a gift), and I gotta say, it's a way better way to wake up than any cell phone alarm could be. Very gradual and gentle.

The phrase to search for is "Philips wake up light", on Amazon or whatnot. They make a few models, but the prices start around $60.