On my Ubuntu 11.04 64-bit system, this morning the Update Manager wanted to install the 2.6.38-10-generic kernel, so I let it. I haven't noticed any difference except that memory no longer seems to leak. Usually, after awhile the memory usage increases gradually and doesn't drop much, even when I close programs, but since installing the new kernel it seems to return to "normal" (about where it was after reboot) when I close programs. Of course, I don't really know if this is due to the kernel or to something else. Does someone out there know if this was a fix in the kernel?
I'm glad for the improvement, but don't really know what brought it about.