pdfTeX is an extended version of TeX that can create PDF directly from TeX source files and enhance the result of TeX typesetting with the help of PDF. When PDF output is not selected, pdfTeX produces normal DVI output, otherwise it produces PDF output that looks identical to the DVI output. An important aspect of this project is to investigate alternative justification algorithms, optionally making use of multiple master fonts.
Re: out of date
This was only a problem for the stable 1.x branch. If you need the latest bleeding edge you can always try the beta releases.
And now with 2.x teTeX is up-to-date.