at the price point of the 3g model, you can buy a powerful netbook that can do anything the ipad can + anything an entry level laptop would.
Actually, for the price of the entry-level model ($499), you can buy an entry level full fledged laptop. While there are certainly some tricked out laptops around (I paid $1280 for mine, some years back, and it's, well, even better today), the average price paid for non-netbooks laptops in the USA last year was $550. You can get a netbook that's more powerful than the iPad for about $300.
Or less.. any netbook is going to be more powerful. The basic 1.6GHz Atom processor is simply faster than the 1GHz ARM Corex A8 that Apple's put in their custom "A4" SOC. The entry-level netbooks also generally use the Intel GM500 graphics core, which is very weak by PC standards. It's licensed from PowerVR, and it's actually the fastest GPU that PowerVR offers. The iPhone 3GS, Motorola Droid, and Palm Pre all use somewhat lesser PowerVR GPUs. The iPad itself is still a bit of a debate, GPU-wise (some say PowerVR, some say its using a new design from ARM themselves).
If you like the tablet idea but don't care about Windows (or iPhoneOS), wait for the various tablets using the nVidia Tegra 2 chipset. These will at least offer netbook-or-better performance, and still get you that 10+ hours of full AVC HD playback. I kinda-sorta like the idea of the long-battery-life tablet, but it needs to have USB so I can connect my cameras.