Last week I took a briefing with Ryan Gavin, director of platform strategy at Microsoft, who wanted to talk about the positioning of Microsoft's Live platform in the market.

When I asked Gavin what he thought was the cornerstone service of Windows Live, he said Windows Live Hotmail without missing a beat. I shouldn't have been surprised.

comScore said Windows Live Hotmail ranks only behind Yahoo Mail in the United States. The site grew to 47.1 million monthly users, up 3 percent from the 45.8 million the research firm tracked in July 2008.

Gavin said Live Hotmail's ability to connect "communications and sharing in its permanency is one of the things that I'm most excited about and I think it's probably one of the most powerful and oftentimes overlooked things in this space."

Sensing I was on dangerous ground, I calmly suggested to Gavin that Google's Gmail might be why Windows Live Hotmail is overlooked. Like many others, I used Windows Live Hotmail a decade ago when it was just Hotmail. I abandoned Web mail for several years (other than as a backup) and did not even jump on the Gmail bandwagon until 2007, but that was it.

I explained to Gavin that when I tried Gmail, just like Google search, there was no reason for me to leave. It offers text messaging right from a PC to a person's cell phone, video chat, to-do lists, document integration and a number of other helpful Web services that Live Hotmail just doesn't offer today.

Why use this?

When I can use this?

How does Microsoft compete with that? Gavin told me a successful Web mail app is the one that helps users efficiently maintain their social connections.

"With respect to Hotmail, we're very clearly focused on that home to work efficiency, that young busy professional or busy mom, nailing that best inbox for that experience. It's not clear right now where Gmail's prime focus is. With Google Labs, there is a lot of features that get rolled out regularly that are somewhat unfocused and it's not clear who should be applying what when and what they are all accruing up to other than a whole set of sometimes interesting, sometimes more whimsical things that are being rolled out. So I think nailing the scenario of what the inbox is best at will be a competitive differentiator and will help dictate the mailshare battle into the future. The reality is most people don't want another service and they don't want yet another inbox in their life."

Ah, the Gmail is a cute, unfocused experiment argument. That position carried weight in the past. It certainly put doubt in prospective business users' minds when considering a migration from Microsoft Outlook to Gmail.

But Gmail is a lot more mature and is finally out of beta, so that argument no longer suffices. You can't point to Mail Goggles (though Gavin no doubt had this tool in mind when he characterized Gmail as "whimsical") and say it undermines Gmail as a Web mail app.

I'd say Gmail is focused on providing rich Web services and Google is certainly racking up users by the bushel. Gmail is the rising star of Web mail applications, drawing 37 million unique monthly users in July.

It's only five years old, but it has already passed AOL mail. I expect it won't be long before Gmail passes Microsoft, though it's got years to go to catch Yahoo's 106 million users (from comScore's July rankings).

Gavin also argued that Web mail users will need a place to store documents and photos, as well as e-mail conversations, pointing to Windows Live Skydrive and Windows Live Mesh as a way to store users' lifestream of content and access it from anywhere.

He basically said Live Hotmail offers a convergence of Web services Google doesn't. I'd contend Google Gmail, through its increasingly tight integration with Google Apps, fits the bill.