Google are planning to increase their ad copy length up to 200 characters.

Basically, titles and display urls will remain the same, but advertisers will now have the capacity to write a description which is 200 characters long.

Ads that currently look like this:

Google Ad programmes
Can your website make more money?
Monetize and enhance your content...
www.google.com/adsense 

Could be expanded to look more like this:

Google Ad programmes  www.google.com/adsense  Can your website make more money? Monetise and enhance your content pages by displaying relevant Google ads that match what visitors are looking for on your site. Try our advertising programmes today.   

You need to create both the long and short ad copy versions in your campaign and they will appear alternately.  I'm still not sure how these longer ads are going to be displayed on Google or within their partner network, I'm assuming they will be displayed at the top of the page where the higher ctr ads are positioned - otherwise everything could look a bit too cluttered.

At the moment, everything is still being tested and only a small number of advertisers are able to increase their ad length.