Greg Kroah-Hartman has announced that the Linux 2.6.32 kernel stable tree will be a "long-term" stable release that should be maintained for two to three years. This stable branch should live on as long as a flow of stable, back-ported patches continue to arrive in Greg's email inbox. In contrast, the stable branch of the Linux 2.6.31 kernel has stopped as of yesterday. The last long-term stable kernel, Linux 2.6.27, will also be closing up in H2'2010.
Greg's kernel stable tree status update can be found on his blog. Meanwhile, development of the Linux 2.6.33 kernel continues in full swing.