What do you mean by functionality? If you think the shiny surface of your product can be that much of an after-thought (i.e. not considered alongside the functionality you choose to code), you either have wonderfully abstracted code (or lots of useless code) (in which case you're delaying it because you can), or you have a different definition of Artist than I do (in which case you're delaying it because you've confused design with gloss).

I agree with that. Artist doesn't mean someone to make the logos, it means some one to design your site and make it pleasing to the users. I've found that the sooner that happens in the process the better. In fact I'm starting to lean toward the 37Signals method of making the layout work before it's even attached to the code. Thinking about how things happen from the user's pov can really help your final product.

I've come to realize that how things happen from the user's pov / what the user sees IS your product. That's what the user's paying for. The user cares as much about what your app purports to do as how your app does it. The how determines whether the user will save more time/money/resources with your app than without it.

That said, I do agree with original commentor that it's possible to get all the functionality working (the interface, the AJAX, the domain model) and then have someone take your visually uninspired HTML+CSS and turn it into something beautiful. Sometimes that's all a hacker will need, and sometimes a hacker will need much more.

Exactly my plan. And as joelonsoftware pointed out, some "design" problems are really engineering problems (like the wheel of the ipod). I can solve those, and then some artist can create fancy logos, fonts and stylesheets.

Good luck. I'd love to hear how you feel after you've launched.