I ran this example code with 2 polyCubes in scene.
import pymel.core as pymel
pymel.select('pCube1', 'blinn1')
print pymel.ls(sl = True)
print pymel.ls(sl = True)[0]
and this is my output
[nt.Transform(u'pCube1'), nt.Blinn(u'blinn1')]
pCube1
I know the elements inside this list are PyNodes, but printing them gives out a string type name of the node. Is there anyway to access the PyNode directly from this list?