debtree 0.8.0, including the new option to display reverse dependencies, is now officially (or rather: unofficially) available.

The new feature is of course documented in the man page, but also on the website.

And now I think the time has come to port the script to perl. If I manage that I plan to upload the package into the archive as version 1.0.

P.S. debtree now also supports generating trivial graphs:

$ debtree --max-depth=0 dpkg

Funnily enough that same graph is less trivial for apt. Support for --max-depth=0 was added to allow to generate graphs showing only reverse dependencies.