Berlin-based Erik Spiekermann, designer of the ubiquitous Meta, has one called spiekerblog. According to a recent interview on typeradio, he created it so he wouldn’t have to answer so many emails asking the same questions over and over.
Finally, one of the first weblogs I ever knew about was Grant Hutchinson’s splorp.blog. As a type designer, he was responsible for a large portion of the old Image Club type library. Image Club is no longer around, but, after several changes of hands, many of their fonts still are available through Agfa Monotype, including his ever-popular Fajita. Grant is now at Veer in Calgary, Alberta, which he helped start up with his Image Club cohorts. [Update: Veer no longer exists, so I removed the link.]