Krishna, I've modified the title.
What I've gathered in the article is that this isn't a potential cure for a chromosomal disorder (in fact, the UW researcher interviewed in the article said as much), but rather opens up doors for potential treatment (namely, gene replacement therapy) for those with Down syndrome. More importantly, it gives researchers a great tool to study developmental differences of trisomy 21 cells vs. the cell from the same individual with the trisomy removed.
Nice find.