The image below is supposedly a Peter Weyland journal entry, and it comes from Reddit; a Redditor found it in the bonus features on the steelbook version of Prometheus. While Eldon Tyrell is never mentioned by name, the heavy handed language indicates that it's talking about replicants and Blade Runner - which indicates that perhaps Prometheus and Blade Runner take place in the same universe.
Eh, maybe. I hope not. And if we're going by what's established in Blade Runner - specifically the date - it seems unlikely. The Prometheus tie-in videos included a TED talk with Weyland that took place about four years after Blade Runner's 2019, and in the TED talk he goes on about humanoid robots as if they're a pretty new thing. Blade Runner establishes that replicants are not brand new. The timelines don't really work out on a basic level. Also, the prevalence of off-world colonies doesn't quite fit in with the feeling of space travel as a big deal in Prometheus.
But Ridley Scott, fresh off pooping on the lawn of Alien, is looking to poop on the lawn of Blade Runner, so it's possible he might be creating connections. Whatever comes next for Blade Runner, it's possible Scott will be forced to softly reboot the original - if they release Blade Runner 2 in 2015 the original film's 2019 setting will be really, really weird. So maybe he will be tying the two franchises together.
I vote that this is a cute Easter Egg intended to snare the eyeballs of those with a passing knowledge of the two franchises. And I vote that Ridley Scott keeps it that way.