trogau

You can query core, plugin, and themes individually, or check all at once.
It defines four new methods:
<ul>
<li>xmlrpcCoreUpdateCheck – checks core, returns true/false</li>
<li>xmlrpcPluginUpdateCheck – checks plugins, returns true/false</li>
<li>xmlrpcThemeUpdateCheck – checks themes, returns true/false</li>
<li>xmlrpcUpdatesCheck – checks all of the above, returns an array of trues/falses.</li>
</ul>
The plugin was created primarily for WPUpCheck (http://trog.qgl.org/wpupcheck/), a simple 
Windows application that remotely polls a WordPress site to see if updates are available.

XML-RPC Update Check

This plugin provides XML-RPC methods for checking the update status of WordPress websites.

George Stephanis

Chip Bennett

This plugin adds some options to your Settings > General page, letting you specify how auto-upgrades should function, without the need to specify constants or add filters by hand.

Update Control

Auto update WP core -> work!
Auto update themes -> work!
Auto update plugins -> work!

but...

Auto update self hosted plugins -> work only one! (Manual update by hand also work only one, i don't know why.)
Auto update self hosted themes -> work only one! (Manual update by hand also work only one, i don't know why.)

---------------

Auto update core send email -> work!
Auto update plugins/themes send email -> not working! (Is its default functional to not sending email from these type of update?)

Work as expect.

Cool

This adds some options to your Settings > General page that let you tweak auto-updates.

XML-RPC Update Check vs Update Control