  Based on a previous ansatz by Zel'dovich for the gravitational energy of
virtual particle-antiparticle pairs, supplemented with the Holographic
Principle, we estimate the vacuum energy in a fairly reasonable agreement with
the experimental values of the Cosmological Constant. We further highlight a
connection between Wheeler's quantum foam and graviton condensation, as
contemplated in the quantum $N$-portrait paradigm, and show that such
connection also leads to a satisfactory prediction of the value of the
cosmological constant. The above results suggest that the "unnaturally" small
value of the cosmological constant may find a quite "natural" explanation once
the nonlocal perspective of the large $N$-portrait gravitational condensation
is endorsed.
