Android lib or libs?

If you use the Android command line to create your project, it'lldefault to libs/.It turns out that the Android Ant tasks are set to lookin libs/ bydefault.

See $ANDROID_HOME/tools/ant/main_rules.xml:

 name="jar.libs.dir" value="libs" />

If you just care about Eclipse, you can use whatever youwant.

In newer revisions of ADT (revision 17 onwards), the Ant-basedbuild system and the Eclipse plug-in are aligned so that theybehave the same way. This means, by default, only the jars that arepresent in the libs folder are included in the final apk file.These jars would automatically appear under "Android Dependencies"in your Eclipse project.

For more details please refer here.http://tools.android.com/recent/dealingwithdependenciesinandroidprojects