In reply to Ramblin dave:
I don't think radios have anything to do with it... breaks have been going away and being caught since cycling in a peleton started.
there's a wide range of motivations at play between the various teams and riders.
The "big GC" teams for instance couldn't give a stuff about the breaks unless there is someone in the break that could threaten their leader's GC position.
On a mountain stage there is motivation to get riders into the break so that when the team leader catches the break they can gain the help from a lesser team mate (for a limited period) this is a huge advantage to the team leader - both psychological and physical
On a flat stage, the GC teams are less interested and only really seek to keep their leader out of trouble (unless a rival team's leader gets into trouble - then they will push hard. Instead it's normally the sprint teams seeking to control the break but the different sprint teams won't want to take more than their fair share of the chase for fear of not having the power to dominate the run in to the finish.
For riders in the break the motivation varies from "being in the shop window" and gaining publicity for the team (who might be too weak to get any stage wins or GC contention), to go for the intermediate sprints (either for their own campaign or to thwart that of a rival). In the mountains there is the real chance of a spotty jersey if they can get in all the breaks on mountain days. Plus on the occasion the break makes it you have a much greater chance of winning the stage if it's you against the 4-5 people in the break than if you were to compete in the whole peleton. - this is also a prime reason why breaks fail so often in the last few KM - it's not necessarily because the pack is stronger, often it's because the 3 or 4 riders up front stop working together and instead think of how they can save energy to beat their break away fellows, and therefore slow down significantly.
The lone break away though is where the real prestige is (and the potential for real heartbreak) Tony' Martin's reputation is built on audacious solo efforts (a couple of heart breaking catches n the last 20m of the race and a few where he just made it (not to mention a few world TT tittles)
The combativity award is given out to reward these riders (normally the one that's been out in the break the longest) and gives the team and sponsors a good photo op on the podium at the end of the day
Post edited at 21:08