I think the question we must ask, is the following: if SETI @ home was or has already found alien signals will they be able to reveal it.
On that theory...
I have always believed that if the signal was found, some governments (if not all and especially organizations like UN) would attempt to keep it a secret. Trying to prevent world hysteria and global chaos.
Because, yes, we SETI enthusiasts will probably be overwhelmed and overjoyed by such a discovery, but the rest of the world may be frightened to a whole new level knowing that some other (possibly more evolved) beings are out there.
And this idea will bring chaos and disaster.
If you look at human history and how in the past couple of millenia we've waged wars against people that were technologically inferior, I can understand that some will think that it could mean the end of humankind should we discover that we're not alone.
However, light takes a long time to reach us, as do radio waves. And a while back I found a video on YouTube that had somebody explain that if aliens would look at us with a massive telescope at a distance of several light years, they would probably see a planet with dinosaurs. And therefore not find our planet interesting to investigate.
Looking at how we scout the skies for signals, probably any signal that we find will be centuries old and the civilization that had send it might already be extinct. It would probably be a scream for help as they knew their planet was doomed.
Now, if you look at how aliens have been portrayed in novels and movies over the last century our imagination runs wild. We've imagined them as being friendly weird looking creatures curious to learn (as in E.T.), or technologically superior, human looking beings trying to make new friends (Vulcans in Star Trek). We've seen them as killing machines that don't need technology to kill (Aliens). And we've seen them as pilots of massive machines that can kill dozens in a single blast (War of the Worlds).
The question you ask may be "Will SETI (or any government) reveal what they find if they find anything?"
The question I ask is "What will the aliens do once they've discovered we've been listening to them?"
Here on earth, if you stumble upon a secret encrypted mail from some government agency you may risk jailtime.
But what if aliens thought you might have been eavesdropping on them, will they annihilate the entire human population?
I would love to see the day that SETI finds something, that the world rejoices and all of humankind will come together and make peace knowing that we're not alone. That we send a "hello" back and be visited by friendly beings that will teach us how to better ourselves.
I would love a scenario like the movie "Contact" to become a reality.
But I think that governments would intervene the second that SETI says "We've got one!".
Only time will tell.