Indeed. There are only a very few stars which are near enough to show a slight shift in their position (relative to the rest of the stellar background), such shift being a result of the earth's motion around the sun. Photos taken at six-month intervals reveal these shifts. The difference is in our perspective, being at opposite ends of our orbital diameter every six months. This is called a parallex shift. Other than that, the stars just don't move enough for it to be noticeable (generally).
Because we know the size of our orbit, and the angle at which we observe the shifted stars, we can easily calculate the distance of such stars. Picture a very elongated isosceles triangle with its base perched on the earth's orbit, one angle anchored at each six-month position of the earth, and with the very acute angle ending at a point which is the star in question. Drop a line from that star perpendicular to the earth's orbit, and it will hit the sun, giving you a pair of right triangles. The rest is simple geometry. For either right triangle, we know the base (the radius of earth's orbit) and we know the angle at which the star is observed, thus we know the size of the other sides.
Because one Cepheid variable just happened to be near enough, we could determine its distance, and thus its true magnitude for that distance, and now we can use such stars as guideposts for determining distances of very distant clusters which contain such variables.
Right you are, PH.
The Cephied variables, whose period of variability is directly related to it's mass, and hence to it's luminosity, are often referred to as the "yardsticks" of the Cosmos" (or, for those of you accustomed to using the MKS system, "metersticks of the Cosmos.") By measuring the period of variablity and the apparent luminosity, we can calculate the distance required for a Cephied of that period to have the obseved brightness.
It's a darned convenient feature of the Cosmos for those Astronomers who aren't too busy wanking away the night "reading" Penthouse.