  We answer the question posed in the title above by considering theoretically
the electron-electron interaction induced many-body effects in undoped
(`intrinsic') and doped (`extrinsic') 2D graphene layers. We find that (1)
intrinsic graphene is a marginal Fermi liquid with the imaginary part of the
self-energy, ${Im}\Sigma(\omega)$, going as linear in energy $\omega$ for small
$\omega$, implying that the quasiparticle spectral weight vanishes at the Dirac
point as $({ln}\omega)^{-1}$; and, (2) extrinsic graphene is a well-defined
Fermi liquid with ${Im}\Sigma(\omega)\sim \omega^2\mathrm{ln}\omega$ near the
Fermi surface similar to 2D carrier systems with parabolic energy dispersion.
We provide analytical and numerical results for quasiparticle renormalization
in graphene, concluding that all experimental graphene systems are ordinary 2D
Fermi liquids since any doping automatically induces generic Fermi liquid
behavior.
