Be careful here, that is and old website and you are misunderstanding how Amazon supports PDF on the Kindle.
1) Since that article was written, and hence not mentioned, Amazon has updated the firmware to actually support true PDF but all you can do with that is read PDF, search PDF, jump to a page number, and bookmark (rabbit ear) a page location. The rendering is perfect and requires no conversion, but the PDF is shrank down to a 6" screen. If the PDF is made for a book usually 9" your okay but if the PDF is targeted for a letter size the PDF fonts will too small to read.
2) The article you referenced, and is still true today, is that Amazon provides a feature to turn (read convert) your PDF to MOBI/AZW (Kindle native format). For the non-techi that the process is transparent. You just email yourself the PDF and your kindle receives a MOBI file. MOBI files you can highlight, search, copy, annotate, bookmark.
There are drawbacks to the conversion process, one the PDF must not be protected, second PDF to MOBI conversion is not that great. It's good enough for text base PDF, but once the PDF start getting complicated the conversion process starts having problems.