I just bought Empire Earth. I noticed in the corner of the copyright notice Sierra On-line. Could my wildest dream be true?

i don't think they own the rights

The rights to Empire Earth were bought by Rebellion. Which is why it's on GOG.

Rats! :-( *cries and writes a song about it*

It's true; GOG has bought the rights from Rebellion,
However, since most of the games in the Rebellion deal were originally published by Sierra, I'm optimistic about it and hope there are some OTHER games in that deal as well ;-).

don't you mean Activision?

Well, Sierra still technically exist, though under the assimilation of Activison Blizzard.

Ground Control is another one. I bought it when Sierra re-released it in their Bestsellers series of budget titles.
Do you know if Rebellion also got the Homeworld games?

I think Relic still own Homeworld

Insider info: Relic still owns Homeworld. ;)
(I don't work at relic. Or actizzard. I just know people who work at Relic).

Well tell those people you know to not only sell Homeworld 1 & 2 on GOG but hurry the hell up with #3

I second this. I'd love to see Homeworld, Homeworld: Cataclysm and Homeworld 2 on GOG. I've played the first and it's expansion but not Homeworld 2.
Are there plans for Homeworld 3 then? Not heard of any before you mentioned it.

The last rumour I'd heard was that there were plans around the time sierra went under but they were shelved until the rights could be confirmed as belonging to relic