Why different available updates in Drush to admin/reports/updates? e.g. in the GUI, I'm told (after running admin/reports/updates/update) that I can update 10 modules. But drush rf; drush up tells me that only three updates are available. Specific example: the GUI says I can update to Views 7.x-3.3, but drush up views says "no code updates available."

I usually prefer to use drush to do the updates since I don't want to pass credentials to my server's user account over the unencrypted web!

But I don't get why drush should report update status differently? Can anyone enlighten me?
Think it was using an old (i.e. Debian Squeeze's) version of Drush. Solution:

Add backports to sources.list

#
# squeeze backports
#
deb http://backports.debian.org/debian-backports squeeze-backports main contrib non-free


Then apt-get install drush=4.5-2~bpo60+1 

Your version number may vary. Check apt-cache policy drush to see what versions are available.