Sony has announced that PlayStation 3 Firmware v3.55 will be releasing soon, but didn't say much more than that. In fact, it was probably one of the shortest posts in the PlayStation Blog's history, from PlayStation Network honcho, Eric Lempel.
It will be a minor update adding a security patch, unlike the 3.50 firmware update in September, which integrated Facebook connectivity into the console.
No official date has been announced as of yet, but PS3 users should expect it soon.
Source: PlayStation Blog