Solid Snake is commonly called Old Snake. Why? It's not his new codename, he is still called Solid Snake, so why do people call him Old Snake? Big Boss aged, but nobody calls him "Old Boss".

Probably it's because of his age, the rapid aging factor and nothing more.

But... if Kojima is playing a game...

SOLID SNAKE -IS = OLD SNAKE

Just a thought and a simple math equalization.

Hmm truly insightful. Props.

Maybe Snake changed his codename to Old Snake. He does seem fairly jaded in all the trailers for MGS 4.

An old, cantankerous man who is too bitter to die ;)

I guess that's what Kojima thinks of Snake now, but some how I doubt that the characters in the game will refer to him as "old snake". Sounds a bit lame. :P

I like Old Snake, But Solid Snake sounded better..

As stated, 'Old Snake' does refer to Snake's age, but the thing is that this isn't really an in-universe name for Snake - it's merely the name which fans have come to know him by.

So yeah, you can relax a little - it isn't really significant to the actual narrative. Just a nickname for fans.

Nevertheless, the reason why Snake's oldness is being emphasised is due to Kojima wanting to convey that Snake's time is nearly up... and that he doesn't have much more left in him. He's just an old warhorse.

Or an Old Killer..

What did he have, was it 6 months to live?

This game is apparently going to tie up many knots, but i bet there will be one tiny one left open somewhere.

A tiny little frayed string coming from one of those knots at the end of MGS4.

Something i bet.

Pretty much what MGS. and Tamashi have already stated.

Not only to show that Snake has aged, but also that he bears the burden of not existing. He is a Snake not created by nature. Big Boss was created by nature, so he truly existed.

Oh, thanks. Great to hear that Old Snake isn't his new codename. It would sound pretty stupid.
"The legendary Old Snake?"

It just wouldn't feel right.