I have the same problem as described here, with a fresh 11.04 install, on an Asus EeePC 900, all updates applied.
After switching from one (full-screen) application to another, the launcher auto-hides while hovering it. Also when you move the mouse pointer to the edge again, the launcher re-appears, but immediately auto-hides as soon as you move the mouse away from the edge. This behaviour is persistent until you hover the Ubuntu icon in the top panel.
I have the same problem as described here, with a fresh 11.04 install, on an Asus EeePC 900, all updates applied.
After switching from one (full-screen) application to another, the launcher auto-hides while hovering it. Also when you move the mouse pointer to the edge again, the launcher re-appears, but immediately auto-hides as soon as you move the mouse away from the edge. This behaviour is persistent until you hover the Ubuntu icon in the top panel.