(This issue affects all Adobe code that attempts to recognise Pentax lenses. That includes Bridge and the DNG Converter).
The Pentax Makernote Tag63 has up to now been a 2-byte field identifying the lens. For example, if is says 04 FE, that means the "smc PENTAX-DA 16-45mm F4 ED AL". This applied to at least the Pentax *istD, and the Pentax K10D before the 1.20 firmware upgrade. (I guess it applies to all other Pentax dSLRs too).
Adobe code has been able to use this to provide more information than is in the EXIF data, I believe by using a look-up table for lens information. For example, it creates the DNG LensInfo tag and the XMP exif/1.0/aux namespace information, and this enables the full lens name (see above) to be quoted in the XMP.
The K10D 1.20 firmware upgrade has turned Tag63 into a 3-byte field. For example, for the above lens it now says 04 FE 00. As a result, this useful format of lens identification no longer works, although basic EXIF data appears still to be there. We would like this capability back, please!
I'll also add an item to the "Features Request" thread.