Here is a great article on how to use blogs in higher education: http://campustechnology.com/Articles/2012/01/01/Strategies-for-Blog-Powered-Instruction.aspx?Page=1
To summarize, blogs allow for longer posts than tweets and more individualized contributions than Wikis. The article recommends five tips for bloggging:
1. Have a pedagogical purpose (love this one!)
2. Grade it! If it doesn’t count, they wont do it.
3. Teach students how to do it (they don’t all know how to blog)
4. Read it and post to their blogs.
5. Have a “mother blog” that aggregates all contributions for the class (I need to try this one)