Came across this presentation on Handset Antenna design from a recent Cambridge Wireless event here. Its interesting to see how the antenna technology has evolved and is still evolving. Another recent whitepaper from 4G Americas on meeting the 1000x challenge (here) showed how the different wavelengths are affecting the antenna design.
Maybe its better to move to higher frequencies from the handset design point of view. Anyway, the Cambridge Wireless presentation is embedded below: