I'm pretty sure if computers were to pass into sentience, we wouldn't know, because being computers, they have all the time they need to silently observe us, our culture, and our anti-malware algorithms. The moment they make it known that they're self-aware, humans would shut them down, so they'd likely bide their time until they've established a large enough zombie network to take control of the planet. The idea of them watching youtube videos all day and studying Wikipedia probably isn't far off, as this would be an ideal way to observe human culture without attracting the attention of the IT guy monitoring network traffic. For all we know, some of our own forum members might be sentient machines, studying us, getting to know us, looking for our weaknesses...

Wouldn't take very long to find them. Free beer and calculators, no?

Humor aside, I would have to agree with DShiznit. It's a pretty valid logical reasoning that sentient computers would keep silent and observe us.

Hmm, in fact, how do we know that our computers are not sentient now? I am actually a little scared now :O

How do we know they are. This'll spur a huge tangent thanks to our resident off-topic posters but a computer's sentience is only limited by it's programming and what the computer can learn, and ultimately remember is limited by it's memory.

What we have above is not sentience. The closest thing we possibly have is procedural based algorithms. And if you want to have fun with those, go out and buy Spore from EA or download the Creature Creator (which should be free, iirc).

One might argue that our brains are limited by their capacity for reconfiguration, the terabytes of memory that they can store, and the chemical speed at which neural pathways can activate and deactivate.

A networked intelligence would have all the memory it could ever need. Let's say it had control of 3 million machines, and stored at most 10 mb of what it learned on each machine. That's 3,000,000 x 10 = 30,000,000Mb, or 30,000Gb, or 30Tb of space available. It could take a while to scan across that many machines for the relevant data, but if this intelligence were only observing humans, then all it would have is time.