As of iOS 5, no you don't. Of course, if you want to import your own movies and songs, you'll need to use iTunes, but otherwise you can activate and use the device independent of any other computer.
But this article's about the Surface, so back on topic. At this point, we simply don't know enough to fairly judge the Surface. The announcement should technically be classified as vaporware because it didn't include nearly enough information for people to come up with informed opinions -- no price, no mention of street date, and very thin description of tech specs. The fact that MS themselves were warning that even those limited specs could change should raise some eyebrows about why they'd be announcing the product if they haven't finalized the design.
Also, it's fairly risky to put so much emphasis on a differentiator (the keyboard) that's an accessory and one that will likely be cloned for other devices before you even get yours out to market.
We're also talking about two entirely different machines here. The ARM-based system is the true "tablet" model, to compete against the iPad and Android tablets. The "pro" Intel version is more reasonably considered an ultrabook with a touch screen, and will compete against ultrabooks and the MacBook Air.
Microsoft has a long history of doing this. They announce a product, and those businesses that have extensive vendor lock-in with them, get the hint that they should wait a while if they are planning purchasing a similar product. It's a variation of Fear, Uncertainty, and Doubt.