I also wanted to do this but I ended up using pdfbook with the command:
pdfbook --short-edge my.pdf
You might also need to change the signature (number of pages being folded), for example:
pdfbook --short-edge --signature 12 my.pdf
[Update and further notes by B. Crowell, 2021.]
pdfbooks2
What appears to be included along with a latex distribution these days, on linux, is not the pdfbook written by David Firth but a reimplementation called pdfbook2, by Johannes Neumann, http://github.com/jenom/pdfbook2 . There is a man page, which seems to closely duplicate the README on the github project's home page. It looks as though Neumann's version duplicates the command-line interface of Firth's.
Printing using a home printer
In addition to this, I found it necessary to spend some time figuring out how to print the resulting pdf file correctly on a low-end home printer that doesn't have double-sided printing. The following instructions are for a printer that outputs pages face-down, with the head of the page at the front.
As I test, I suggest first printing only two sheets (pages 1-4) using the instructions below, to make sure they work for you. This should give you the outer pages of the booklet, and if they look OK, you can just go on and continue printing the other, inner pages.
First print all even pages. Then take the stack of output out of the tray and flip the whole thing as a unit by 180 degrees with the same motion you would normally use if a book was sitting, closed, on a table in front of you, and you wanted to flip it over to look at the back cover. That is, you're rotating about an axis that sticks out perpendicularly from your belly button. Now put the pages back in the paper tray, and print the odd pages.
If you want to bind or staple your booklet somehow, there are various howtos on https://www.instructables.com/ that pop up if you search for "booklet."
pdfpagespackage supports all kinds of page arrangements. – Stephan Lehmke Jun 14 '12 at 16:50