According to this article in Harpers from about 18 months ago (about the start of the Stormhoek phenomenon), there were 56 WINE blogs.
This number was according to the list on the Wine Blog Watch, a useful site created by Jarrett Byrnes in the US.
As a foodie with an interest in wine he helps to bring some order to the chaos of the blogosphere by listing all those wine blogs out there (there is a sort of arbitrary "must be 75% about wine" rule, which is fine by me) and even when they were last updated. Pretty nifty!
This site has just been added (I think the list must have refreshed recently) and now can be found amongst the other 448 currently listed.
448 represents pretty substantial growth for the category, but is a tiny fraction of all blogs. In fact, according to BlogPulse, "wine" is only mentioned in an average of about 0.35% of all posts.
Must do better!
UPDATED & CORRECTED 28/06/2007