Danwei has a very good summary post on the current situation of microblogging in China here. Fanfou (饭否), Digu (嘀咕), Zuosa (做啥) and Jiwai (叽歪) are all down it seems. Only Tencent's Taotao (滔滔) has not been affected for the moment. Danwei points out that its user base is younger and has a different profile than the other micro bloggin platforms. Additionally it does also not allow for search.
We did a quick round of calls with the founders and CEO's of some of the blocked services. The majority was optimistic to be back online soon again, although none of them was able to officially comment on the situation.