Hi, I'm new here, and I love the site but there are so many Good Old Games that are not here.... I have wished on the wishlist for some including Grim Fandango, System Shock 2, The Monkey Island games, Deux Ex...
How likely is it that the games will eventually be available to buy on this site? Have anyone else's wishes come true?

Hi, welcome. Please read the FAQ (link in the Welcome sticky):
Please add *insert game/publisher here* to the GOG library!
GOG has a handy dandy wishlist that you can use to post your requests for games on GOG. Just make sure you search the wishlist to see if anyone else has already added the game you want and if they have, vote for it instead of creating a new entry. Additionally, if you wish to simply discuss the games you want to see on GOG, you can post in the Official Beg Thread: "This Game Belongs on GOG!".

Will you be adding *insert game/publisher here* to the GOG library?
GOG does not release specific information on prospective games or publishers until they already have agreements in place. They will not comment on who or what they are trying to get, only what they do have. Check the site's main page for news on what is coming soon, it gets updated every Thursday.
Now, until this other games arrive (hopefully), buy others. Go wild, and buy games, because games are awesome.
EDIT:
This part might be useful as well:
Why are some highly requested games, such as System Shock 2, not being added to the catalogue?
GOG tries to get every game they can, but sometimes it is a difficult process to find the correct rights holder, secure permissions to sell the game, get gold masters of the games, modify as necessary to make the game work on modern OSes, etc. It's not that GOG is intentionally not adding a highly requested game, its that they can't unless or until they can meet all those requirements. That certainly doesn't mean you shouldn't keep requesting and voting for games, though. The more interest we can show, the more "ammunition" GOG has to bring to rights holders to convince them to allow their games to become part of the GOG library.

Well, they are trying to get as many games as possible, and I expect they would love to get the popular games from the wishlist because it would greatly increase sales.
However, many of the more popular games (including several of the top ten) are difficult to get because of those that own the copyrights to them. Electronic Arts for example has a large amount of games under its banner, but it is currently not allowing them to be sold for whatever reason. I hope they, and the other publishers, change their minds.

When you wish upon a star
Makes no difference who you are
Anything your heart desires
Will come to you
If your heart is in your dream
No request is too extreme
When you wish upon a star
As dreamers do
Fate is kind
She brings to those who love
The sweet fulfillment of
Their secret longing
Like a bolt out of the blue
Fate steps in and sees you through
When you wish upon a star
Your dreams come true

FWIW, I mentioned Pro Pinball: Timeshock way back on the original wish-list forum thread, and now we have three out of the four Pro Pinball tables available on GOG!
However, given how gargantuan the wish-list is, I'd be inclined to suggest that most games that get released here were probably added to it at some point :)

This is starting to sound like a broken record, but don't people read the stickies at the top? Oh well.
Welcome to the GOG community. It is a great place to hang out and talk, relatively troll free! This is a class community after all.

As sad as it might seem, i would think it would be nigh impossible to secure the rights from either Lucasarts or EA. Lucas arts being greedy, and EA being just plain evil.

If LA's problem was greed, then they would be jumping all over the opportunity to make money off their old titles. The real problem is protectionism. LA is paranoid about protecting their IPs and controlling every aspect of them, including distribution.

Clearly LA needs to do some torrent searches. Their crap is being pirated all over the place, so they might as well at least release a legal version.
EA will probably come around eventually. They're slower than molasses in January and thicker than a brick.

Wow! That post is so.............................useless..........as usual......

it gave the answer.

If Lucasarts still won't give up the rights to their games, might I suggest an intervention?