Is the Duflo polynomial conjecture open?
As far as I know, Duflo's conjecture is still open.
Let me make several remarks:
- Duflo's conjecture actually says that the algebra of invariant differential operators on a symetric space is isomorphic to the $\mathfrak k$-invariant part of $S(\mathfrak g)/(h-\chi(h),h\in\mathfrak k)$, where $\chi$ is the character given by half the trace of the adjoint action of $\mathfrak k$ on $\mathfrak p$. this shift by a character did not appear in Cattaneo-Torossian paper and this was very surprising... there was indeed a mistake in that paper, which is corrected in Cattane-Rossi-Torossian: http://arxiv.org/pdf/1105.5973.pdf
- Duflo's conjecture is indeed more general. It holds for general reductive homogeneous spaces: it claims that the center of the algebra of invariant differential operators is isomorphic to the Poisson center of $\big(S(\mathfrak g)/(h-\chi(h),h\in\mathfrak k)\big)^{\mathfrak k}$.
- Rybnikov's result mentionned in Alexander Chervov's comment prove a localized version of it for Riemaniann reductive homogeneous spaces (i.e. it holds on the level of fraction fields).