The iPad has basic multi-tasking with music playback but what people really want to do is shuffle through 3-4 apps at a time all with them running in the background. This isn't something that appeals to me even on my 8-core desktop. The most I will do is have iTunes, FireFox, and Word open at once when writing a paper.
As previously stated, the big rumor is that iPhone OS 4.0 (which will be a free upgrade to current iPad owners) will support true multi-tasking. Given the hardware in the iPad, iPhone 3Gs, and iPod touch, this multi-tasking will likely be limited in some way. Windows Mobile 7 has multi-tasking but it isn't "real." A program will run, you can start up another one, and the previously open app will be in a pause mode. Most mobile developers (whether it be for iPhone OS, WebOS, Android, or Windows Mobile) believe that we are still a ways away from true multi-tasking on these portable devices.