See Bailey, J. (2011, January 18). Using MLA and APA citations on your blog. [Web log message]. Retrieved from http://www.plagiarismtoday.com/2011/01/18/using-mla-and-apa-citations-on-your-blog/
In reviewing "how to do an APA citation for a blog posting", I found a lot of disagreement among various sites. The APA Blog uses [Blog post]. Here's the example:
Freakonomics. (2010, October 29). E-ZPass is a life-saver (literally) [Blog post]. Retrieved from http://freakonomics.blogs.nytimes.com/2010/10/29/e-zpass-is-a-life-saver-literally/
However example 7.76 of the 6th edition of APA's Publication Manual uses [Web log message]
In any case Bailey in his blog post on Plagiarism Today has some suggestions about how to incorporate properly-formatted citations in blogs.