What is the sure fire sign that a company is moving into a more 'business-like' phase of its development? Usually the hiring of sales talent is the best indication. So the rest of the marketing world should be preparing themselves for a 'new' Twitter very soon as the social media powerhouse has hired some sales players. AdAge reports Want to buy an ad on Twitter? Now there's someone to call. The micro-blog service, which still classifies itself as "pre-revenue,