A featured WebmasterWorld thread asks a good question, does rotating the content on a page hurt your search rankings.
You need to break this question down into how much content is being rotated in and out. If the whole page changes dynamically all the time, then it may cause a problem. If there are sections on the page that change on refresh, then it may not cause a problem. If the content on the page changes throughout the day, like a news site, then it wont cause much of an issue at all.
The big thing here, in my opinion, is to keep users in mind. Will it confuse your users to have the content changing all the time?
Imagine an e-commerce site with featured products on the home page. You can implement the featured products to dynamically rotate based on page load or you can cache the featured products to remain constant for a certain time period. If a shopper comes to your site and likes a featured product but then comes back and can't find it, it can be an issue.
On news sites or blogs, users understand that new content is added often. So users know what will be on the home page today, may not be on the home page tomorrow. Same with sites designed specifically to change on reload, like the Hot or Not web site (great viral site).
WebmasterWorld moderator, caveman, has a nice response:
There are lots of factors here that we don't have precise information on, but that's OK, because there is also a fair amount of existing knowledge out there about sites that constantly change content on the homepage, and for the most part, it just isn't a problem. IMO, Quadrille's point that this won't help in terms of strict SEO, is a legitimate one, but I never look at SEO anymore in that tight a context.The reality is the the dominant search engine uses a very links based algo (they all do, really), so while I am a big believer in on-page optimization still mattering, let's get this in perspective...
The title of the page (most important onpage element) is presumably not changing, nor are important subheads, high level page text, and important site nav elements. If those things are not present, they probably should be (especially in this case). If those constant elements are present, and considering the importance of backlinks, the SE's have more than enough info to effectively rank the page.
Further discussion at WebmasterWorld.
