This could be great news for iOS. AFAIK, this is the first K/V DB that could be built for iOS (c++) and has a free license that is compatible with the AppStore (Tokyo Cabinet uses LGPL and the author has shown no interest to me in adding a static linking clause, Berkeley DB requires an expensive commercial license, etc).
Not key/value, but Mobile CouchBase (CouchDB) supports iOS and apps using it have been approved for the App Store.
An interesting point to note is that Mobile CouchBase is primarily written in Erlang, so porting any existing key/value stores is not dependant on their native language being C or C++.
True. I haven't tried it and it looks promising, but currently it depends on packages like Erlang, Spidermonkey, and OpenSSL, so adding Mobile CouchBase to an app means increasing its size by about 42MB.