Is there any actually observed excited state of a "hypervalent" main-group molecule that actually involves d-orbitals?
One candidate involves calcium, of all things. This paper by Krieck et al. [1] reports the synthesis of a dimeric calcium(I) complex $\ce{[(thf)3Ca\{μ-C6H3-1,3,5-Ph3\}Ca(thf)3]}$ in which the calcium atoms are bonded to each other and there are two unpaired electrons in antibonding orbitals of the aromatic ring system. 

DFT calculations show that the orbitals containing the unpaired electrons have a significant contribution from calcium 3d orbitals which have the same symmetry as the ring antibonding orbitals.  A model of the compound is given below.


  


References


Krieck, S.; Görls, H.; Yu, L.; Reiher, M.; Westerhausen, M. Stable “Inverse” Sandwich Complex with Unprecedented Organocalcium(I): Crystal Structures of [(Thf)2Mg(Br)-C6H2-2,4,6-Ph3] and [(Thf)3Ca{μ-C6H3-1,3,5-Ph3}Ca(Thf)3]. J. Am. Chem. Soc. 2009, 131 (8), 2977–2985. DOI: 10.1021/ja808524y.