As for twitter, according to Fleet (2009), it is a different kind of commitment. Each post takes just little time. That can give Twitter the appearance of requiring much less of a commitment than writing a 'traditional' blog.
Bloggers use Twitter much more than does the general population. In a poll conducted by Penn, Schoen & Berland Associates in May 2009 for The Wall Street Journa’s “All Things D” conference, just 14% of the general population used Twitter – but 73% of respondents in this survey do (including 83% of Corporates and 88% of Self-Employeds). Those who use Twitter say they do so to promote their blogs, bring interesting links to light, and to understand what people are buzzing about. 50% of Part Timers say they use Twitter to market their businesses. Other uses of Twitter, like interacting with companies (24%), politicians (11%), and celebrities (9%), are much less popular (Technorati.com, 2009).
According to Technorati.com (2009), 26% of bloggers who also use Twitter say that the service has eaten into the time they spend updating their traditional blogs – though 65% say it has had no effect.

Image 2. (Technorati.com)
Both are valuable tools, and both are effective in their own way with different purposes.
Reference:
Fleet, D, 2009, Blogging vs. Twitter: A different kind of commitment.
Accessed 29 October, 2009
http://davefleet.com/2009/02/blogs-vs-twitter-different-commitment/
WordPress.org, Introduction to Blogging,
Accessed 29 October, 2009
http://codex.wordpress.org/Introduction_to_Blogging
Technorati.com, Day 5: Twitter, Global Impact and The Future Of Blogging - SOTB 2009
Accessed 29 October, 2009
http://technorati.com/blogging/article/day-5-twitter-global-impact-and/


