The new version of Ubuntu (8.10 aka Intrepid Ibex) was released yesterday. Because I heard of many improvements in this version I immediately got a copy and installed it. The overall impression is awesome! And the best of all - VisualVM is available as an Ubuntu package right from the Canonical repositories.
Just open the Synaptic Manager, type "visualvm" in the quick-search box (btw, this is the best thing since sliced bread ;) and you can install VisualVM with all the dependencies. The download size is quite hefty (cca. 300MB) since it downloads the whole open-jdk, mysql and i-dont-know-what-else but in the end you have full-blown java development environment with the bonus of VisualVM nicely registered under "Applications/Programming/VisualVM" menu shortcut.