meebo, a browser-based service that enables users to chat from multiple platforms at once, including Yahoo, MSN Messenger, AIM and Gchat, has just announced its compatibility with the iPhone.

While the site in theory has always been iPhone-compatible, it now sports an interface that mimics the ease-of-use of the standard version, and isolates iPhone specific tools when users log in from their mobiles.

Using meebo for the iPhone does not require a download, a major boon for the web-native offering. Users merely log into meebo and it resets itself per specifications for the phone.

The functionality enables users to log into multiple accounts on one buddy list, glean from their chat history and preview active conversations before responding, streamlining the mobile chat process so that it mimics the ease of computer-based conversation.

meebo has been characterized as the fastest-growing instant messaging clients. And in May, it developed a series of strategic relationships with ad and media partners, which were then able to build branded chat rooms on the platform.

Mashable has snapshots of how meebo appears on the iPhone.