The reason of the "shame" of the
challos, applies to mezonos as well,
since ordinarily the blessing of
mezonos is recited before the blessing
of ha-gafen. Indeed, some poskim rule
that cakes and pastries should be
covered during the recital of the
morning Kiddush.(Kitzur Shulchan Aruch
55:5; Teshuvos Levushei Mordechai O.C.
kamma, 46. Even according to this
view, however, only the person making
Kiddush [and others who are partaking
of the wine] needs to cover his
mezonos items. All other participants
do not need to cover their mezonos,
since they are not "shaming" the
mezonos by listening to Kiddush; Harav
S.Z. Auerbach (Shemiras Shabbos
K'hilchasah 47, note 125).
But not all poskim agree. Eishel
Avraham Orach Chaim 182 holds that
mezonos items do not need to be
covered during Kiddush because only
challos - which can be used for
Kiddush and are being bypassed in
favor of wine - are being "shamed."
Mezonos items, however, are generally
not eligible to have Kiddush recited
over them, so they cannot be "shamed"
by the wine taking precedence over
them.(Ta'amei ha-Minhagim, 365,
Kuntress Acharon; Az Nidberu 2:)