PMN Dashboard
Take a look at the free PMN Dashboard for a great overview of the four major handset manufacturers.
"Keep track of the performance of the four major handset manufacturers from quarter to quarter, tracking metrics such as unit shipments, profit margins and average selling prices."

For example, the above chart shows the year on year Q1 performance - measured as a combination of margin, profit, ASP, market share, unit shipments and sales.
If you read the dashboard you will get the impression that Nokia remains strong but is being challenged by Sony Ericsson with its increased device sales while maintaining its average selling unit price and profit.
PMN is running the innovative Mobile User Experience (MEX) conference in London next week. I’ll be there if you wish to meet up. I’ll be helping put together the insights shared at the conference that will be published to delegates in a comprehensive post-event report. Register now if you are interested as there are just a couple of passes remaining.