The short answer is yes. The long answer follows.
There are not many web presences as easily accessible as the blog. It is free and easy to use. This makes it a great learning tool for the classroom, especially the budget friendly classroom. However, the tool is only as good as its learning outcome. Therefore, it is important to get the most out of it. I will discuss two uses of a blog in the area of education.
1. The blog as an interactive forum for academic discourse
No one can deny that social interaction is an important part of learning. Sharing and discussion/debating of ideas allows a learner to use prior knowledge as well as the knowledge of their peers. Blogs allow two crucial interactions.
The first is the ability to respond to a post. This allows discussion of a topic. Not only does the poster of the comment benefit from creating the comment, but the final viewer who sees both post and comment benefits greatly from both sources of knowledge.
The second is the ability to view media and other sources of information. A blog can act as a gateway to reliable trustworthy content on the Internet. For instance, if the teacher is the creator of the blog, they can ensure that they link to reliable content and show reliable videos. This way, the learner does not waste time trudging through useless garbage (not that learning how to do this is not useful knowledge). Time is the currency we have in the classroom. We must use it wisely.
2. The blog as a collaborative learning experience
Learning in groups is a proven method. Sharing ideas and creating new ones together can benefit a learner greatly. A blog is an excellent collaboration tool.
One method used in classrooms is to have students learn through teaching. The steps to prepare to teach require that a student knows the content, and the outcome is a great assessment of what the student has learned. By having students create a blog together, they can research, discuss, share their ideas in a blog post, and share their blog with others. Each group member can even contribute separately through a comment, and the other learners can comment as well, aiding the learning of the blog post's creators.
A goal of all forms of education is to create an environment supportive of learning. We want to use the tools we have to foster learning and make sure we have the necessary resources to find the information we need. A blog can do all of that. Just like any technology, the blog is a tool that can be used in many ways. It is up to the creator/moderator to ensure it is being used in a way that is supportive of the learning objectives.