A new firmware update with build number 14.4.A.0.157 has been certified by the PTCRB for the Sony Xperia Z1, Xperia Z1 Compact and Xperia Z Ultra. This appears to be a minor revision over the previous software that was certified, but never released, with build number 14.4.A.0.155.
If Sony does release this firmware it would replace build number 14.4.A.0.133 (which only hit selected carrier devices) or the older 14.4.A.0.108 that saw a global release.
Xperia Z1 build number 14.4.A.0.157 certified for C6902, C6903 and C6906 variants
Xperia Z Ultra build number 14.4.A.0.157 certified for C6802, C6833, C6843 and C6806 variants
Xperia Z1 Compact (D5503) build number 14.4.A.0.157 certified