The biggest news in the athiest/sceptical sphere at the moment is probably the "atheist bus campaign" - by which I mean that it is the story that has garnered the most attention among the news/opinion sources I read on a regular basis.
When I first got wind of the idea a little while ago, I greeted it with mirth and interest; I thought it was about time we had some secular, atheist or agnostic messages out in the "real world". It would help stimulate debate, and perhaps make people realise that they're not alone in feeling detached from religion (a feeling I'm sure is more prevalent than generally believed).
Now that the campaign has well and truly taken off (last I heard they had exceeded their target by a staggering £75,000 or so), it's even turning up in the "Politics" section of my RSS feeds - at Liberal Conspiracy and even a spoof by the great Beau Bo D'Or.
Of course, being sceptics, there has been little agreement on whether the slogan that had been settled upon was the right one to use. The first objections centered around the use of the word "probably", and this choice may or may not have been down to advertising regulations not allowing more assertive statements. Others have claimed it's too patronising and will not achieve what it aims to.
The most interesting objections come from an authoritative source, Tracy King at Skepchick.org, who expands on her initial misgivings in this comment. As someone who not only works in marketing, but was also a one-time Christian, her opinion is a very well-informed one on this matter. For her, the slogan not only doesn't cut it, but is actually counter-productive. Sadly, I'm inclined to agree.
The question that needs to be asked when designing this sort of thing has to be about what the effect of the advert is intended to be. As far as I can tell, the motivation behind this one is to get people thinking, talking, and questioning religion, and also to put a friendly face on the alternatives - in this case, humanism. So will the chosen slogan have the intended effect? The general consensus among those discussing it seems to be "no". The thread on the UK-Skeptics Forum has now turned mostly toward what the slogan should be.
I have no experience as a slogan-writer so can do little to offer alternatives; but as far as concepts go, I'd prefer one that didn't evoke "God" at all. I feel that a campaign simply promoting rational, free, and intelligent debate would be more beneficial. The biggest problem faced in this regard is how best to word it so that average people will actually look at it and think.
I don't know how far along the process is as far as the advertising is concerned, but if it's at all possible, those organising the campaign should rethink the slogan in consultation with marketing advisers. The amount of money they have raised is a mandate to take it seriously and do the best job they possibly can.