As of f19a445d we added support for OSGi.
The jar task produces the jPOS OSGi bundle (in build/libs directory)
The bundleFull task creates a bigger bundle that include jPOS dependencies in its lib directory under the name jpos-1.9.3-SNAPSHOT-bundle-full.jar (precompiled versions can be downloaded from jpos-1.9.3-SNAPSHOT.jar and jpos-1.9.3-SNAPSHOT-bundle-full.jar in the jPOS Bundles repository.
There's a new qnode module that you can use to test the jPOS bundle (if you don't have an OSGi container already installed). You can go to qnode directory (sibling with the jpos one), run gradle installApp and then copy your bundle to the 'bundles' directory.
Here is a full session:
cd jpos gradle bundleFull
cd ../qnode gradle installApp
cp ../jpos/build/libs/jpos-1.9.3-SNAPSHOT-bundle-full.jar build/install/qnode/bundle build/install/qnode/bin/qnode
This should launch Q2 installed as a Bundle in an OSGi container (in this case, Apache Felix).