As a notice at the official site says, the Maxis sites will be down from tomorrow until tuesday 27 August. That means you cannot visit thesims.ea.com, simcity.ea.com and simgolf.ea.com during this period. The sites should be back online by the time it gets wednesday for Maxis. As there are only major upgrades to the network (and so not the sites), you probably won't see any changes to the sites afterwards.