I've thought about this to, but it doesn't appear to be a problem. As the speakers in either case will be rather close to each other, you're bound to lose a great deal of separation regardless of where they are. On my N810, with speakers on either end of the device, the only occasions where I truly notice separation, is if the device is literally resting on my forehead -- not practical. Otherwise it may as well be a mono speaker.

Thankfully people seem to enjoy the external speakers on the Tab. Tim Bray was shocked by the outstanding balance in his review.

For true separation, though, you'll want to get a good set of cans (headphones) -- and not all headphones are created equal. You should check out headphone.com for great recommendations. Set your spending limit for headphones to around $100 and make a purchase that you will not regret for YEARS to come.
Here's a very good set: http://www.headphone.com/headphones/etymotic-mc5.php ($80)

As I understand it, the Galaxy Tab has Bluetooth v3.0 which is SIGNIFICANT when it comes to audio. As I understand it, it uses the WiFi frequencies to deliver superior bandwidth than previous versions of bluetooth. The reason this is significant in this case, is that wireless audio via the A2DP protocol, while adequate, must be compressed before sending which results in audio quality loss.

Sadly, it doesn't seem that there are protocols/devices that take advantage of BT3.0 -- it's a young technology (apr 2009). But I'm eagerly awaiting a good pair of BT3.0 headphones that can carry lossless audio. Good headphones are a life altering experience, especially when they block out external noises. Wireless makes it *that* much better.