According to the survey from this article, Windows Mobile is favored by field workers. Interesting quote from the article around mobile project spend this year:
"Spend on mobile workforce technology will either increase or at worst stay the same, with 41 per cent of respondents saying the current economic conditions would have no impact on mobile purchases."
Not surprising given that mobile LOB is an enabling technology to help improve efficiencies and reduce cost. For sure, Microsoft has always had a very strong focus on LOB solutions including a great reference application in the Windows Mobile Line of Business Solution Accelerator, updated for Visual Studio 200 and available here.
If you are interested in building a LOB mobile solution, check out the LOB Solution Accelerator along with the documentation on ADO.NET Synchronization Services for Devices available on MSDN. Be sure to download the latest version of Sync Services for Devices and SQL Compact Edition from the Microsoft Download Center as well. (SP1 is the latest for both as of January 2009).