next_post() and previous_post() are both scheduled to be depricated in 1.5.1. Their replacement functions will be next_post_link() and previous_post_link()
The way this is written makes it seem out of date. Perhaps the functionality has been stable and so it hasn't needed updating? If so perhaps something like "Apllies to 2.9.2" could be added at the top? --bentrem 22:33, 1 April 2010 (UTC)