First off - zenphoto is great! Thank you so much for providing such a usable image gallery for free!

My question revolves arround wanting to set the login cookie to expire with in hour of its first issue. We are going to use zenphoto for an album for a youth group and as such want to restrict access as best we can. I dont want people looging on in schools and the next person on the machine to be still logged on.

The cookie for admin login is stored by auth_zp.php. You can change the timeout there.

thanks very much..... what about the "guest" cookie?

If you will install the current nightly build all the cookie handling has been changed to use a define--COOKIE_PESISTENCE. The definition is in functions-basic.php circa line 31.

is the current nightly build reliable enough for people to use daily?

Generally so, but you should, of course, test it first.