Mozilla's notes from its weekly meeting says "there will be no more updates for Firefox 3.0.x."
Mozilla had planned to stop supporting Firefox 3.0 in January but delays in releasing 3.6 forced them to keep 3.0 alive a bit longer.
But now version 3.0.19 will be the final version of the open source Web browser. Mozilla is also working on Firefox versions 3.5.9 and 3.6.2.
According to Mozilla's schedule each of these new browsers should be released on Mar. 30.