Bloggers worldwide are abuzz over a report that Hossein Derakhshan, a popular Iranian-Canadian writer once dubbed the Blogfather, has been arrested in Iran. Iran's Jahan News Agency, which is said to be tied to Tehran's theocratic government, reported the arrest Monday, saying Mr. Derakhshan, 34, was suspected of spying for Israel. Mr. Derakhshan, also known as Hoder, keeps a blog in both Persian and English. The daily blog ominously stopped publishing late last month, and between each blog and his Facebook account, there's been no online trace of Hoder since Oct. 30. But one rival blogger, who didn't want to...