eMarketeer published a study about online advertising spending in the UK, present and future (bold mine):

Advertisers will spend £3.4 billion in 2008, a rise of 27% from the year before, according to new online ad spending figures released by eMarketer. Internet advertising spending will continue to show double-digit growth through 2010, passing £4.3 billion in 2010 and exceeding £5 billion in 2012.

Even considering that the UK market isn't the world market, it's a very good insight, which allows me to say we are on the right track to growth. In this case, numbers speak for themselves: