Not sure if it's just me but when I click on the installation guide link on the downloads page I do not get the installation/upgrade guide.

It's not just you. I can't see it either.

All user guide content seems to have vanished.

They are there when I try.

There seem to be a lot of articles which seem to have lost their actual content.
For instance: http://www.zenphoto.org/news/zenphotos-object-model-framework

I do see this as well and it even worse, they are missing on the backend completely! As far as I see it only affects Zenpage news articles and pages.

I fear we have a server issue here as there are encoding issues with my name that have not been there before.

The use guide is back. If you find anything else missing let us know.