Microsoft may have as little as a year to take command of the mobile phone platform, or the opportunity will be lost. (Image from Petrified Truth.)

At the 3GSM conference in Cannes, France, they gave it their best shot.

The mobile broadband business is at what Gandalf called "the pause before the plunge." Enough equipment has been deployed so broadband can be advertised. The time has come to define the experience and see if any money can be made from it.

We've argued here for some time that mobile phones are entering the computing mainstream, but does that mean they want to be computers? Microsoft isn't alone in thinking so -- the Cannes show featured PalmSource and even Linux equipment. (Image of the show entrance from the BBC.)

Of the three, Microsoft seems best-positioned to make headway because they're speaking the carriers' language (ARPU, meaning Average Revenue Per User) and because they can put big money behind the tough job of upgrading users.

Reaching the new networks requires a new phone, and home field advantage here belongs to Symbian, a British company that has been Nokia's vendor of choice for years.

While Microsoft deliberately made headlines with Nokia at Cannes, it was for a version of the Media Player, not Windows Mobile. Nokia was also feeling pressure, offering to take its name off phones when carriers insist on carrying all the branding themselves.

The key questions, however, are going to be asked on the street, and wtihin the next few months (since mobiles go through several generations of product each year). Will people spend real money to get what Microsoft is offering? Will they actually use it and raise carrier ARPU enough to justify the broadband investment?

That's the way to bet, but there are no guarantees. The plunge is coming. The answer may be here before a prediction can even be absorbed.