YES - Kent Ferguson, analyst, Nielsen Mobile
Advertising pounds follow audiences, and more than three billion people have mobile phones.
Mobile as a viable advertising channel is dependent on the presence of several factors, such as advanced consumer devices, high-speed networks, reasonable data packages, compelling content, and subscriber interest in advanced mobile functions.
In countries where these building blocks are in place, mobile is entering the mainstream as an advertising channel.
In the UK, about 10 million people have recalled seeing a mobile ad; in the US, that number is almost 60 million.
As more countries lay down the groundwork for an effective mobile advertising channel, mobile's share of the ad-spend pie will grow.
NO - Peter Markey, head of marketing, RSA (formerly Royal & Sun Alliance)
There have been so many false dawns for mobile advertising - with WAP and 3G - but still it hasn't taken off.
Mobile as a medium does not offer clients enough space to cut through and stand out from the other content on mobiles.
There has been a fair amount of mobile advertising by clients focused on promotions that have worked, such as discounts and special offers, but that's largely it.
Mobile can play a role, but it will not become a major channel, and you won't see clients pulling spend from radio or TV, for example, and putting it into mobile.
Online TV is an emerging channel that will become a main ad channel, but mobile doesn't offer clients the same interactivity.
For some brands, such as lifestyle, mobile advertising may work, but for most it does not have enough reach.
YES - Natalie Bell, digital planning director, Manning Gottlieb UK
It's just a matter of time before mobile becomes a mainstream ad channel, but there are still a lot of obstacles in the way of this happening soon. We are definitely seeing some real advances at the moment.
First, consumer behaviour, in terms of increased usage, has fuelled the growth of the mobile web.
And second, the industry has moved to eradicate some of the issues that face agencies when using the channel - the recent work from the GSMA and operators is a positive step forward in addressing some of the problems with standardisation of platforms, formats and measurement.
However, we still need to see better demographics and targeting capabilities that reflect the strength of the channel as a personal medium.
Planners need to understand the breadth of opportunities that mobile offers as a communications channel - mobile advertising is about so much more than banners and SMS.
YES - Tom Smith, head of consumer futures EMEA, Universal McCann
There is no doubt that mobile will become a mainstream advertising channel, because the future of the web is increasingly mobile.
In Japan, more people already access the web via mobile than PC. This is a glimpse of the future towards which we are all heading.
The massive volume of web and data consumed by 3G iPhone users demonstrates that it is simply a matter of waiting for handsets and data speeds to deliver a quality internet experience. Consumer demand is there; for most users, the technology isn't yet.
But it won't necessarily be advertising as we know it: location-based services, quick-response tags and personalised messaging will provide a wealth of inventive opportunities.