"...it's the text messaging feature that's making waves. Under the “Compose” option at the top of the Yahoo Mail sidebar there will be a new option to send a message via SMS to numbers in India, Canada, the Philippines and the United States. To use it, just enter a contact’s name, type in the mobile phone number, and then send the message. SMS threads appear in talk bubbles next to your chat avatar in the Yahoo Mail window..."
Wow. That's one up against GMail. Well, not counting the unlimited storage already available in Yahoo Mail. Imagine, sending SMS messages thru email. And the Philippines is included even!
As you know, the Philippines is one of the top SMS users in the world. To send SMS messages thru Yahoo Mail, will boost up the usage factor here a lot.
Although honestly, I'd still use my GMail more. I find the interface a lot more easier than Yahoo.