There are a number of devices that seem to have a market that overlaps. For example, the Amazon Kindle (the eBook reader) will read books...but we also have seen a market develop for Netbooks...and another market for smart phones...and another market for laptops.
Apple has introduced even more confusion in to the marketplace with the introduction of their new tablet computer, the iPad. The media described it as a larger looking iPhone. Now, you may read the description and say "hey, this sounds a lot like a Tablet PC, and those didn't work out that well for Microsoft!"...if you did, you have a lot in common with me because I said that. Then again, there are times when technologies come before their time. Perhaps Apple will be the company that bring this type of machine mainstream!
I worry that all these varied options may eventually harm consumers. With all the different options out there, something is going to become obsolete. If you invest $300 in an Amazon Kindle, and they lose the battle to Apple in the eBook market, what happens to you? It's like the people who invested in the HD-DVD format (which was a format of high-definition DVD that was made obsolete by the competing Blu-Ray format).
I am always interested in the inter-battles going on between big Internet and technology companies. Google is battling Microsoft ...who is battling Apple...who is now battling Amazon.
Only time will tell....