"458854" is a high stakes cash game player from the country which has produced some of the best poker players in the world, Finland. He joins a list of superstar poker players from the country which include Patrik Antonius, Sami Kelopuro and Ilari Sahamies.
He has not all of a sudden started to play the high stakes games as he has grinded his way through the mid-stakes levels to progress to playing the nosebleed stakes on Full Tilt. He can be seen at both the NLHE and PLO tables playing either heads-up or in the six-max games.
It can be assumed that he played under a different screen name on other sites to build up his bankroll but it seems that he has kept this information very private as little is known or even rumoured about him on the forums.