  We report a detailed investigation of GdO$_{1-x}$F$_{x}$FeAs (x = 0, 0.07 and
0.14) samples by means of high-field/high-frequency electron spin resonance
(HF-ESR) together with measurements of thermodynamic and transport properties.
The parent GdOFeAs compound exhibits Fe long-range magnetic order below 128 K,
whereas both doped samples do not show such order and are superconducting with
T$_c$ = 20 K (x = 0.07) and T$_c$ = 45 K (x = 0.14). The Gd$^{3+}$ HF-ESR
reveals an appreciable exchange coupling between Gd and Fe moments, through
which the static magnetic order is clearly seen in the parent compound. Owing
to this coupling, HF-ESR can probe sensitively the evolution of the magnetism
in the FeAs planes upon F doping. It is found that in both superconducting
samples, where the Fe long-range order is absent, there are short-range, static
on the ESR time scale magnetic correlations between Fe spins. Their occurrence
on a large doping scale may be indicative of the ground states' coexistence.
