Since last night, most likely due to the posting of video of the Tibet demonstrations, some of which is reposting of material from major news organizations (such as this, from CNN). Via Danwei and Shanghaiist. CNN and BBC have been regularly blacked out and overseas news websites have been  crawling (although not blocked). Stand by for the Olympic repercussions.

Imagethief echoes the Shanghaiist and highly recommends using a subscription VPN service. Much faster than TOR, much more convenient than proxy web pages, and well worth the relatively modest cost.

See also:

ESWN's translation of a blog post from a Han Chinese witness to the demonstrations. 

John Kennedy's roundup of Chinese blogger comments on the situation at Global Voices.

Mutant Palm's continuing translation of Chinese tweets on the situation. Yes, I have been known to scorn Twitter and its clones in the past, but there is something to be said for its immediacy.