The original site at for Glogster at www.glogster.com is generally blocked by school districts because it is listed as a social-networking site.
In order to allow teachers the opportunity to use Glogster the company created an educational site.
At the Educational Glogster site you can create accounts for up to 200 students to log in under your main account. As the teacher you retain the accounts under your main account which provides you access to their accounts too.
Here is a brief tutorial:
Here are a few examples of how teachers are utilizing Glogster with their students in the classroom: