It seems that Barcelona is desperate to keep Lionel Messi and not let Argentina national football team to take him for playing in Olympic Games 2008. Argentina has a tough group in Olympics 2008 along with Ivory Coast, Australia and Serbia. So, It will be very tough for Argentina to do well in Olympics.
On the other hand, Barcelona has much bigger problem at hand. Last season, they disappointed everyone by not winning any trophy. So, this season Barcelona is under pressure from everyone to perform. Undoubtedly, Lionel Messi is the best player of Barcelona. So, they need to keep him from the start of the season.