Yahoo! has acquired del.icio.us, which provides a social bookmarking model for web users. del.icio.us is essentially a collection of favorite bookmarks that are shared on the web. By tagging web content with one-word descriptors, users of the service makes it easier for others to find the content. Financial terms are not disclosed.del.icio.us is privately-held and based in New York City. It has received seed financing from Union Square Ventures, Amazon.com, BV Capital, Marc Andreessen, Esther Dyson, Seth Goldstein, Josh Koppelman, Howard Morgan,...