although juhu is still in early beta stage, I will try to provide basic help on installing and using juhu within the next couple of lines.
1. downloading and installing juhu
after downloading the zip archive and unpacking it, you should see the juhu app icon where ever you extracted it to (you may drag it to your applications folder, but you don't have to). a double click should fire up the program. when running it for the first time, a sheet will be displayed and prompt you to enter your account information. at this point you have to be a bit carefull - you have to enter your normal jaiku screen name but the personal key is not your normal password, but a special key that can be obtained from http://api.jaiku.com. once you have done that, you should be able to send a post and read the public stream. (remark: users of the quicksilver jaiku plugin won't have to enter their account information, since juhu uses the same keychain entry)
2. using and configuring juhu
you can post an update to your presence by entering the text in the provided bubble, adding an icon and a location and hitting the send button.
in the titlebar of the window you find a + (plus) button which toggles between the small and the big view mode, the x (close) button closes the window, but doesn't quit juhu at all. if you click on the statusbar icon, the window will be closed or opened. please note, that when the window is open, but hidden somewhere deep under all the other windows on your screen, you might have to click twice in order to see the juhu window again.
there are to ways to quit juhu: you can go to the preference panel (the tool icon) and use the quit button, or you can simply press command+q on your keyboard.
like mentioned earlier, the tool icon will give you a preference sheet. you can select the stream you want to see (public or contacts), the time between refreshes, whether you want to hear a sound on entrienews or not and the error message behavior there. if you like to check your account information (screen name and personal key), just use the "Account information..." button.
any questions on how to use juhu? post a comment!