The official site will be going down for some server maintenance tonight. This is something Maxis tends to do regularly, and they'll be cleaning up a lot of mess on their servers then. They should be back soon though (16 April according to the note), and a SimDay will probably follow a day later. This goes for all Maxis sites, including SimCity and probably the nearly forgotten SimGolf (although it doesn't say anything there). If the TSO site will be taken down is unknown, as that's hosted by EA Games rather than by Maxis themselves. Because of this maintenance, SimCityDay has been delayed until next week.