Ubuntu 9.04, the next Linux operating system release due out by Canonical in April, will not be shipping with the Linux 2.6.29 kernel like many had hoped for. More here

Canonical’s Tim Gardner had said on the kernel team’s list, “Jaunty will absolutely, positively, and without a doubt, release with a
2.6.28 kernel.” Many Ubuntu users — including us — would have liked to see the Linux 2.6.29 kernel inside Ubuntu 9.04, but that simply will not happen. Unless you are interested in building your own kernel, users will simply need to wait until Ubuntu 9.10 when it will ship with the Linux 2.6.30 or 2.6.31 kernels.