Yahoo’s embrace of all things open continues today – expect an announcement in an hour or so that they are expanding their Open Search Platform that we wrote about last month.

In that previous announcement, Yahoo talked about their plans to allow third parties to alter and enhance search results with structured data that may be useful to users. Today, they’ll give more details on the developer platform and will announce support for a number of semantic web standards.

What does all this mean? It means we can expect the web to get itself organized, in a hurry. At stake is a significant amount of traffic from Yahoo search, and anyone else that may choose to build applications on top of this data.

Yahoo’s support for semantic web standards like RDF and microformats is exactly the incentive websites need to adopt them. Instead of semantic silos scattered across the Web (think Twine), Yahoo will be pulling all the semantic information together when available, as a search engine should. Until now, there were few applications that demanded properly structured data from third parties. That changes today.

One example Yahoo director of product management Amit Kumar and others gave me during a briefing yesterday is LinkedIn – were they to mark up user profile pages with microformats, Yahoo search could understand the content and relationships between pieces of content. Yahoo can then present that data in an intelligent way in Yahoo search. “With a richer understanding of LinkedIn’s structured data included in our index, we will be able to present users with more compelling and useful search results for their site,” Yahoo says. Here’s how it will look in search results (see our previous post on Yahoo Open Search for how this is implemented):

Any third party can create mods for Yahoo search that leverage their semantic data (Yahoo will be launching a beta program in a few weeks, along with a developer launch party). Some lucky ones will be added by default to all searches.

A few details are being disclosed now, and Yahoo promises more in a few weeks. They are saying that they will support a number of microformats at the start: hCard, hCalendar, hReview, hAtom and XFN. They will support vocabulary components from Dublin Core, Creative Commons, FOAF, GeoRSS, MediaRSS, and others. They will support RDFa and eRDF markup to embed these into existing HTML pages. Finally, Yahoo will support the Amazon A9 OpenSearch specification with extensions for structured queries to deep web data.

Erick Schonfeld wrote a post in February urging Yahoo to open up search completely to compete with Google. Yahoo isn’t heading in that direction, yet. But they sure look like they might get there eventually.