There's not really much to the seemingly eternal Star Wars or Star Trek argument. Both are set in space but, really, they're different styles of science fiction with their pros and cons. That said, we can still have a little fun setting them against each other -- literally. You know, Star Destroyers blowing up the Enterprise and all that.
Even with the two franchises in the hands of JJ Abrams, it's unlikely we'll see an official mash-up, beyond the odd background Easter egg and even then, that's an ask. Instead, we'll have to make do with fan efforts, like this one from Alex Luthor.
It combines the newer Star Treks with a mix of fresh and vintage Star Wars to create a battle-filled and uh, emotional, trailer where the two universes fight each other for... well... the stakes are not entirely clear.
The clip is mostly composed of creatively-cut footage, though there's a bit of image manipulation to help it gel. I can't say the old-school Starfleet has much hope against the Empire's mighty forces, but who knows -- with some help from the Klingons and the recalcitrant Romulans... anything is possible.