Yahoo just announced that they are going to implement the support of the NOODP meta tag, beginning tonight. In order to launch this change, they will be reindexing web content, resulting in typical ranking changes and page shuffling. So expect some possible movement of your rankings.
If you don't want ODP (DMOZ) titles or snippets used by Yahoo, place one of the following meta tags on your pages.
META NAME="ROBOTS" CONTENT="NOODP"
META NAME="Slurp" CONTENT="NOODP"