The prevailing halachic opinion is that the mitzvah for Kohanim to bless the congregation, as contained in our Parasha, is in force today (Sefer haChinuch 367; and subsequent Halachic authorities). In practice, the custom in Jerusalem and most places in Israel (except the Galilee) is for Kohanim to bless the congregation daily (and twice on Shabbat). Outside Israel, Kohanim generally bless the congregation only on the Shalosh Regalim (the three pilgrimage holidays) and Yom Kippur (Rema, Orach Chayyim 128:44; this, at least is the Ashkenazi custom).
Among the later halachic authorities, including contemporary authorities, we sense discomfort with the custom as noted by the Rema, and find an attempt to offer a reasonable explanation for the failure to fulfill the mitzvah of the priestly blessing in Chutz la-Aretz. (In fact, the Aruch Hashulchan [128:64] says that some have written that it is a bad minhag to do away with this biblical commandment on a daily basis and that several Gedolim attempted to reinstitute it, but to no avail. Ed.)
The Shela haKadosh (1558 - 1628) writes that the Jews of Chutz la-Aretz are blessed through the priestly blessing given in Israel. Some contemporary halachic authorities suggest that it is appropriate for Jews outside Israel to specifically request of a Kohain in Israel to have them in mind when delivering the priestly blessing.
This mitzva is just another example not only of the primacy of Eretz Yisrael, but also of its influence on Jewish communities outside Israel as well.