Here is a post by Mark Herrmann and James Beck on their blog called Drug and Device Law about their views on lawyers at big firms who have their own blogs. This is a topic I have written on before and that I could fill volumes on, but for now I will defer to the widely-read and wildly popular Messrs. Herrmann and Beck. I think every firm approaches blogs a little differently, but as partners at 2 of the largest law firms in the world, their views deserve attention.
UPDATE: Here is the view on the issue by the blog called Adam Smith, Esq.