The previous latest Beta Labs build was '208' and, interestingly (and annoyingly), phones with this build are not offered the new version through Ovi Store - only 'Launch' is shown. So, if you really want the latest and greatest version of Nokia Social, you'll have to side-load it from the SIS file, like I did. The install over build '208' worked perfectly.
Also missing at this point is acknowledgement of the new version when starting the existing Nokia Social application, for updating in-app and over the air, but maybe this too will be switched on at some point?
Comments welcome on how well (or badly) the update went for you...