The case can surely be made that artificial intelligences will be alien -- different in origin and nature from us.
In my earlier look at AI (which concluded that AI can be more than a trope), I opined that our lack of success in achieving AI may stem from anthropomorphism. Never mind that we can't define intelligence, awareness, or consciousness. We characterize intelligence (per the Turing test) as communicating -- hence (much unstated waving of hands) thinking -- indistinguishably from us. And so AIs in fiction often think like humans and even strive to behave like humans.
Consider, for example, Mike (named for Mycroft Holmes, Sherlock's smarter brother) in Robert A. Heinlein's The Moon Is a Harsh Mistress. Or, more recently, Brittney the teeny-bopper AI in Richard A. Lovett's "Sands of Titan" and sequels in Analog. (I'd love [for a change, no pun intended] to offer a link. Lovett has no personal web page and somehow avoided having a Wikipedia page.) Both AIs simply emerged, bypassing our continuing lack of understanding of how we might implement an AI. Both take humans as role models. I've written stories using a similar premise -- recognizing as I did so that I was committing a trope.
There's much to be said for exploring scenarios beyond our images somehow becoming embedded in silicon. In my latest novel, Fools' Experiments, I showed an AI evolving from very primitive software. Artificial life inside a computer may have some parallels with carbon-based life -- but surely there will also be many differences. Look how much aquatic and land-based life vary. How different might an in-computer entity be from a biological being evolved on a planet?
That's but one type of alien AI. Another is the AI so advanced (think: beyond the Singularity) that it can't be represented directly to mere humans -- the author keeps the AI character offstage. Example: the "Eschaton" of Charles Stross's Singularity Sky.
AIs can be alien even when built in their programmers' image: when the programmer is an alien. That's one theme in my InterstellarNet series of stories, about a radio-based interstellar community. (Physical travel between stars being impractical, the humans and aliens alike transmit AIs to represent them. Surprise! the alien AIs are alien, and follow alien agendas.)
As always, there can be hybrids. In Code of the Life Maker, James P. Hogan plants alien factory automation on Titan -- and it mutates. It evolves, over eons, into a whole AI- and robot-based ecology. Neat premise. Neat story.
So AIs can be alien. Even alien alien.