  A new class of infinite dimensional representations of the Yangians
$Y(\frak{g})$ and $Y(\frak{b})$ corresponding to a complex semisimple algebra
$\frak{g}$ and its Borel subalgebra $\frak{b}\subset\frak{g}$ is constructed.
It is based on the generalization of the Drinfeld realization of $Y(\frak{g})$,
$\frak{g}=\frak{gl}(N)$ in terms of quantum minors to the case of an arbitrary
semisimple Lie algebra $\frak{g}$. The Poisson geometry associated with the
constructed representations is described. In particular it is shown that the
underlying symplectic leaves are isomorphic to the moduli spaces of
$G$-monopoles defined as the components of the space of based maps of
$\mathbb{P}^1$ into the generalized flag manifold $X=G/B$. Thus the constructed
representations of the Yangian may be considered as a quantization of the
moduli space of the monopoles.
