The idea of three kingdoms (Telestial, Terrestrial, and Telestial) is well established in Mormon theology. What may be less established is the fact that these kingdoms of glory exist as “rungs” right now in the world in which we currently live.
What creates these rungs is law. The law you live is the rung of the ladder you have reached. The rung you cling to determines which kingdom you shall inherit. The Prophet Joseph Smith said:
“Paul ascended into the third heaven, and he could understand the three principal rounds of Jacob's ladder-the telestial, the terrestrial, and the celestial glories or kingdoms, where Paul saw and heard things which were not lawful for him to utter. I could explain a hundred fold more than I ever have of the glories of the kingdoms manifested to me in the vision, were I permitted, and were the people prepared to receive them.”
Jacob’s Ladder is an illustration of the ascent of man, by the law he keeps. The Doctrine and Covenants tells us:
“[speaking of the resurrection] That bodies who are of the celestial kingdom may possess it [the earth] forever and ever; for, for this intent was it made and created, and for this intent are they [the meek] sanctified. And they who are not sanctified through the law which I have given unto you, even the law of Christ, must inherit another kingdom, even that of a terrestrial kingdom, or that of a telestial kingdom. For he who is not able to abide the law of a celestial kingdom cannot abide a celestial glory. And he who cannot abide the law of a terrestrial kingdom cannot abide a terrestrial glory. And he who cannot abide the law of a telestial kingdom cannot abide a telestial glory; therefore he is not meet for a kingdom of glory. Therefore he must abide a kingdom which is not a kingdom of glory.” 
So, if we keep a Celestial law now, can we enter the Celestial Kingdom now?
What say ye?
 Doctrine and Covenants 88:38
 Joseph Smith Jr., Messages of the First Presidency, vol. 1, James R. Clark, The Prophet's Discourse from II Peter, May 21, 1843, Deseret Book.
 Doctrine and Covenants 88:20-24