Hi Kirk,
Both the timezone and the daylightsavings information is actually in the makernotes (only). But as you (correctly) determine the timezone from the makernotes, the daylightsavings should be taken into account as well.
I have uploaded 2 sets of files (nef and jpg each), one set is straight from camera (HRB_....) and the other is after ingest (ING_....). This is the output from exiftool with the relevant tags selected:
$ exiftool -G0:1 -a -Exif:DateTimeOriginal -IPTC:DateCreated -IPTC:TimeCreated -XMP:DateCreated -Timezone -Daylightsavings HRB_6342.NEF ING_6342.nef HRB_6343.JPG ING_6343.jpg
======== HRB_6342.NEF
[EXIF:ExifIFD] Date/Time Original : 2014:07:25 21:10:33
[EXIF:IFD0] Date/Time Original : 2014:07:25 21:10:33
[MakerNotes:Nikon] Timezone : +01:00
[MakerNotes:Nikon] Daylight Savings : Yes
======== ING_6342.nef
[EXIF:ExifIFD] Date/Time Original : 2014:07:25 21:10:33
[EXIF:IFD0] Date/Time Original : 2014:07:25 21:10:33
[IPTC] Date Created : 2014:07:25
[IPTC] Time Created : 21:10:33+01:00
[XMP:XMP-photoshop] Date Created : 2014:07:25 21:10:33+01:00
[MakerNotes:Nikon] Timezone : +01:00
[MakerNotes:Nikon] Daylight Savings : Yes
======== HRB_6343.JPG
[EXIF:ExifIFD] Date/Time Original : 2014:07:25 21:11:01
[MakerNotes:Nikon] Timezone : +01:00
[MakerNotes:Nikon] Daylight Savings : Yes
======== ING_6343.jpg
[EXIF:ExifIFD] Date/Time Original : 2014:07:25 21:11:01
[IPTC] Date Created : 2014:07:25
[IPTC] Time Created : 21:11:01+01:00
[XMP:XMP-photoshop] Date Created : 2014:07:25 21:11:01+01:00
[MakerNotes:Nikon] Timezone : +01:00
[MakerNotes:Nikon] Daylight Savings : Yes
4 image files read
On the ingested images, the timezone info added to the IPTC:TimeCreated and XMP:DateCreated should be +02:00, not +01:00.
On a related note, if the camera does not provide the timezone/dst info, it looks as if the local timezone is used, but I think PM should not fill one in at all in these cases! (because there's too big a chance that it is in fact wrong!
If you need more samples, let me know.
Cheers,
Hayo