JC is currently the most OP profession in WOTLK, while that may change in the future it is far and away better than any other profession right now. You get a daily quest which lets you make dragon eyes (sells for 150-400g), you get 3 JC-only gems with much better stats than blue gems AND are prismatic, which is huge -- you can socket them anywhere and they will match any color. For tanks especially this is great, since you can do 3 +def gems while still gearing up and hit the def cap without any issues. There is also a great starting tanking trinket.

Enchanting is an ok profession. The self-enchants are mediocore, it takes an insane amount of money to level enchanting from 400+, and there are so many enchanters (and no current "rare" recipes) that you will rarely make any money beyond DEing stuff. Blue items can be vendored for almost as much as shards sell for (sometimes more), and green BOEs can be DE'd by anyone.

For a prot pally I would suggest a combo of either JC/mining (+50 sta buff is nice), JC/BS (2 extra sockets, goes well with JC), or maybe JC/alchemy (4 hour flasks). Its likely when patch 3.1 hits another prof will become the flavor-of-the-month, especially as epic gems are brought back into the game. Currently however pretty much all the top raiders are converting one of their professions to jewelcrafting, and for good reason.

btw i have every prof (except engineering) covered on my team, it makes it really nice. never have to ask someone else to craft something and i can herb/mine/etc as I fly around.