dpkg doesn't have dependency support. There is a way around it but that would require you to make a local database (and thus you would already know the dependencies) and it is considered obsolete (...).
Does it have to be command line? (server install?) If so also have a look at
apt-get -f but be careful: solving dependencies after install could have you end up with a broken system.
gdebi (gui frontend) used to be able to do this but got replaced with USC.
How did you download the .deb. Some of the new 11.04 features is the handling of .deb downloaded from a website: it gets opend in USC so dependencies will be solved by the installer.
EDIT based on comment by andrew:
sudo gdebi foo-1.2.3.deb
would do the trick!!