Light bulbs contain gas, either Argon, Neon or Xenon. They are NOT the same as a vacuum chamber.
"In 1840, British scientist Warren de la Rue enclosed a coiled platinum filament in a
vacuum tube and passed an electric current through it." and "...the evacuated chamber would contain fewer gas molecules to react with the platinum..."
Source:
http://en.wikipedia.org/wiki/Incandescent_light_bulbWhy would anyone bother making a light bulb with a vacuum inside it if light couldn't escape? It'd be completely pointless. Okay, it's not a total vacuum, but as has been pointed out before, such a thing does not exist on the scales we are talking about.
Sci, thanks but those vacuum tubes have gas in them:
That was interesting info you gave, but I get the distinct feeling you were cherry-picking. This was at the top of the same page you quoted from:
"In electronics, a vacuum tube, electron tube (in North America), tube, or thermionic valve or valve (in British English) is a device controlling electric current through a
vacuum in a sealed container."
and this was a little lower down:
"
The vast majority of modern day tubes consist of a sealed container
with a vacuum inside..."
Here's a home-made vacuum triode:

Also here, you can clearly see that only the filament is glowing, and it is lighting the entire room:
