Hi. I have been trying to get this working all day now.
It is very important for me that keywords follow my images from viewNX/Lightroom/Picasa to piwigo.
They don't though.. I have installed piwigo 2.0.9 on my server. Set it up nicely to work the way I want.
Downloaded pLoader 1.5 and run it and imported pictures in to it.
Already then I can see I am going to have problems.

The tag area of pLoader is blank. I know I have tags, I can even see them in Windows (windows 7).
So I hope it is just  a bug and continue with my upload.
But, I can not see any tags on my site after upload either. And I can not search for any tags.. :( 
When i go to the Highrez version of the images on my server, again I can read the IPTC info.

Tried following the advice from my administrator page just to see what happens (advice is on bottom of post) but even then I got the response:

Informations are read from sample.jpg
no IPTC information
EXIF Fields in sample.jpg


New advice about $conf['show_iptc_mapping']

Show IPTC Data from your picture:
1 - Copy one of your jpg pictures (a public one) in ./tools/
2 - Rename it as sample.jpg.
3 - Run ./tools/metadata.php
4 - Analyse results to determine which IPTC fields could be useful for your visitors.
Beginners would prefer to keep $conf['show_iptc'] = false,
Advanced users would take care of $lang values and impacts on templates.