What is the spawn code for pine wood in Minecraft?

Vanilla support for this has been added. The syntax is:

/give <playername> <data-value> [amount] [damage-value]

Note that if you specify a damage value, you must specify an amount.

So for this specific case, you would use:

/give <your-name> 6 <how-much-you-want> 1

You can't spawn things with special data attached in the base game, such as pine saplings or colored wool.

You need a mod, like bukkit.

Then, the command would be /give BlueRaja 6:1 64

Update

Ok, I've actually set up a server on my machine and tested this, it appears that with a vanilla Minecraft server the suffices for different types of sapling do not work, so you can only spawn 'plain' saplings.

(Old Answer)

From the wiki it appears to be 6. Try 6:1.