It depends on the conference. Many conferences publish the one page abstract that you're sometimes required to submit with the poster, but not all of them. If you didn't have to write the 1-page summary as part of the submission, don't expect it to be published. The poster itself is almost never published (I personally recommend that you make the poster available on the web).
Despite that, you CAN still list it as a publication on your CV, but posters are generally not worth very much and it's good to compartmentalize them to their own section of the CV so that your (eventual) journal and conference papers get priority.
A bit more description about "weight" and whether you should pass or not:
Generally, the weight of a publication (all else being equal, like let's assume for a moment that every paper's research content is the same) depends on the venue it's in and the type of publication it is. Posters are on the bottom, then short papers, then full conference papers. Usually, you get a poster because the work isn't developed enough to fill up a full paper. One thing to note is that if you "compartmentalize" your work well enough, you should be able to get the poster out and then later extend it to the journal without any issues - that is, if your journal builds upon your poster (quite often by adding more results, more interpretations/implications from the data, more analysis, etc.) then you'll have no problem with having both the poster and the later journal paper/conference paper.
I would like to take a moment to say that while this usually is okay for posters (poster to journal/conference paper), taking this path from a short paper/note to conference paper is often wrought with more problems. Because short papers already present an approach and sometimes results, you need to ensure that the full paper builds SIGNIFICANTLY on the short paper for it to be a real contribution. I've been seeing more recently people highlighting differences between short papers and long papers as a result (ex: "This paper builds upon the work presented in  by adding a thorough evaluation through two lab studies and one industrial field study"). You need to do this because if you don't, and someone does a web search for the topic of the paper, they might find your short paper and then be all like, "So it looks like someone has done this before". Unlike in a poster, where you really don't get that much space to talk about much of anything, you can usually discuss something of substance in a short paper.
Anyway, in general, it's usually okay to present posters and then later expand them into journals or conference papers. Poster presentations are healthy in that they are a quick and easy way to get yourself "out there", solicit feedback from the community, and get further ideas for what you want to do with your work. You can usually use the feedback from the poster session to build upon what you have and get a stronger research direction in the future. But do be aware that you're not "self-scooping" yourself by putting super-important results in a poster, because posters have low impact.