I had been using a G1 for ~1 year, but it died last week. Anyway, Android does multitasking, but not as completely as the N900 does. In Android, lets say you open up the browser and then hit the home key to open up The Weather Channel app. Hitting the home key actually puts the Browser into a sort of sleep mode, not completely exiting out like the iPhone would do but not fully running in the background like the N900 would do either. You can switch back to the browser and it appears to return back to where it was, however it was not actively running in the background and was possibly even paged off in order to regain the memory (especially in the case of the memory-lacking G1).