Matt Cutts has tweeted that Googlebots are now intelligent enough to read content loaded via ajax or javascript. This means that Ajax content, such as used on Facebook or Disqus are now available to the Google spiders. This makes Ajax a more suiltable method of delivering dynamic content if you want to preserve search engine visibility. Also you can now use client side dynamic content generation using javascript - so for example, you could detect a browser's country of origin and dynamically load content in the correct language. Previously, Google would have ignored the whole content.

One of the possible problems you could face is that the content might look out of date quite quickly if there is a regular change in the content.