Google just release a new version of the SDK that handles Shared Libraries!
https://developer.android.com/tools/projects/projects-eclipse.html#SettingUpLibraryProject
ADT 0.9.7 (May 2010)
Library projects:
The ADT Plugin now
supports the use of library projects
during development, a capability that
lets you store shared Android
application code and resources in a
separate development project. You can
then reference the library project
from other Android projects and, at
build time, the tools compile the
shared code and resources as part of
the dependent applications. More
information about this feature is
available in the Developing in Eclipse
with ADT document. If you are not
developing in Eclipse, SDK Tools r6
provides the equivalent library
project support through the Ant build
system.