If you've been following the Tab's prolonged multicarrier roll-out this month, you're probably wondering why AT&T has priced the Tab at a $50 premium over its competitors Sprint, T-Mobile, and Verizon.
One answer is that AT&T is using the same flexible, pay-as-you-go data plans pioneered on the iPad, priced at $14.99 (250MB/month) and $25 (2GB/month). If you plan on mostly leaning on the Tab's Wi-Fi capabilities, having the option of paying as little as $14.99/month (when you're in a pinch) makes this competitively more affordable in the long-haul.
To sweeten the deal, AT&T is also throwing in a $50 gift card for the Samsung Media Hub movie rental store--which balances the price out if you planned on using the store anyway.
Of course, the other answer to why AT&T set the price high is that it can. AT&T already has the hottest tablet of all time; it doesn't need to eat into its profits to compete.