I've noticed some strange behavior in iTunes 10 regarding the resizing of displayed columns in List view. It appears that I can resize any displayed column in my main library, with exception to the immovable 1st column (the "currently playing or paused" column) or the checkmark column. This is fine.
The problem comes when I try to resize columns on an attached iPod. I can resize some columns, but not all ... that makes no sense! For instance, with my current settings, the optional displayed list view columns for my iPod are (currently in this order):Artist, Track #, Time, Album, Date Added, Size, Kind, Bit Rate, and Rating. In addition to these, there are the 3 default columns: the song order/play status column, and the Name column. I can't resize any of the default columns, nor can I resize these columns: Date Added, Kind, Rating, or Size.
Also, you should be able to resize the columns in the Column Browser, but you can't do that in either the main library OR an iPod library.
While viewing your iPod Library, try opening View Options (on my Mac, it's Cmd-J). Uncheck the columns you can't resize, and click OK. Those columns should disappear. Open View Options again, and recheck them. See if you are now able to resize them. This procedure worked for me on iTunes 9.2.1.