Black Mesa and Aperture Science, the two focal science companies of the Half-life and Portal series exist in the same in-game biverse and, at one point vied for research funding. The Borealis (containing some Aperture Science portal technology) is sought out by the resistance (remnants of Black Mesa and newly freed citizens) for various means.
If you wander around the correct locations in Portal one you see there various slides from presentations that hint at a rivalry between the two companies, both of which were working on similar projects. As well as this, the dry dock for the Borealis is seen in Portal 2.
Teleportation was a major field of study at Black Mesa, and their portals were used primarily in the procurement of Xen crystals, as they were used to transport scientists to and from the Borderworld for research and analysis.
~Half Life Wiki (referencing game events)
Single dimensional teleportation is seen in the second chapter of Half-Life 2, Red Letter Day when the resistance tried to teleport Gordon Freeman to a separate base, and achieved by factoring in 'Dark Energy equations'. In effect the teleportation swings by Xen, and arrives elsewhere on earth
Conversely the teleportation technology developed by Aperture Science is based on portal technology and is in essence instantaneous. The supposed delay in the teleportation of Gordon is due to interference from the combine teleporter being destroyed, otherwise teleportation as developed by Black Mesa is also instantaneous.
Some time before the 7-Hour war (circa 1970, from Portal 2), it is found out that Aperture science is close to completing/advancing their portal technology, sans safety checks:
The Borealis is an Aperture Science research vessel introduced in Half-Life 2: Episode Two. According to Isaac Kleiner, Aperture was working on a promising project, but in their rush to beat Black Mesa for funding, they neglected ordinary safety rules and the ship simply disappeared with parts of its drydock, which earned it an almost legendary stature.
Years later, Judith Mossman, Resistance operative, finds the Borealis and sends a message to that effect to the resistance in White Forest.
I'm fairly sure I've pinned down the location of the Project. It's hard to say how much of it might have survived intact, or whether there's anything remaining that could compromise our work... if it were discovered by the Combine. We'll need to take a close look at it, of course, but I should be able to give a better opinion within a few hours. If the site is where we think it is, then it should be no more than... I'm going to cut this short. We may have been spotted.
The resistance decide from this and now decrypted photos and blue prints that whatever Aperture science developed and is now on the Borealis is either going to be a powerful weapon against the Combine, or too dangerous to be left in the hands of the combine. Either way it signals how the two companies and more importantly stories are intimately linked.