Dataquest released a report called "Gartner Dataquest Says Worldwide PDA Market Suffers Through a Dismal Year in 2002 - Sales Decline As Enterprises Are Slow to Purchase PDAs".
The press release, date 27 Jan 2003 shows the market presence of Palm and Palm OS based devices is 53%, with Pocket PC growing fast. The Sharp presence is minor, with 1.9% of the market. Note the Sharp is the only Linux-based handheld in the table.
The table also shows a decline of 9.1% in shipments of handhelds in 2002, comparing to 2001 shipments.
Read the full press release with figures in the link below.