According from this thing in G.M. this is about Molik
Most Improved Player: Alicia Molik.
We can hear you thinking "Nadia Petrova," but Petrova actually was moving into the Top 30 before getting hurt two years ago; she didn't have to gain much ground from that level. But Molik, despite several injuries, won her first title and reached two finals and reached a career rankings high and looks ready to go higher if she can stay healthy.
JHH should definately win the official WTA most improved player award. THis award means nothing and so won't affect JHH's chances of getting the WTA's award. The only player who could threten her I'd think would be Petrova but she might get comeback player.