Sony reported yesterday that the PlayStation Network was to undergo "significant maintenance" during the 1st of March. However, this has now been postponed until a later date, which hasn't yet been specified. .
The news was delivered via the official Twitter account for the PlayStation Network, where Sony stated: "Update: Tomorrow's scheduled PSN maintenance has been postponed. We'll update everyone once it's rescheduled. Until then, game on."
It's still unclear what the maintenance was specifically designed to address, but stay tuned for updates on the maintenance times and any information regarding the maintenance.
Source: PlayStation Twitter