Adds a sidebar widget to the main site of a WPMU/WPMS install.
If you are running a WPMS (Multisite) blogging network, the issue with most login widgets that you add to the main site’s sidebar is that it doesn’t pull the user’s own blog info. That is why the WPMS Sidebar Login Widget was created. Instead of the user trying to remember the login page of their own site/blog, when a user logs into your main site, the widget will conveniently contain links to navigate to 3 different pages of the user's blog: dashboard, new post page, and profile page.
To make sure it works, activate the User Switching plugin on the main site only to switch to a different user.