[eluser]Jay Turley[/eluser]
It depends on your target audience.
If you feel confident your audience will have modern browsers with Javascript enabled and will not be using assistive technologies like screen readers, then you don't have to worry about it.
What you *could* do is the following. Lets assume you have a "recommended links" section on your home page which will be loaded through ajax.
First, generate your page with a div with an id "recommended_links". Inside it, you can provide a link to a page showing your recommended links for no script-enabled users.
Then, using Javascript, on page load, you would replace the content of the div (currently the link) with the data pulled using ajax.
This would be an example of "progressive enhancement".
HTH