> I believe glob ignores hidden files (on *ix, files with names starting with "."),
> while readdir doesn't.

It depends on how you call glob:
In a directory containing the files aaaa, bbbb, cccc, .dddd, .eeee, .ffff

glob (and similar '<>'):

$ perl -e "print '-> ', join '|', glob('*');"
-> aaaa|bbbb|cccc

$ perl -e "print '-> ', join '|', glob('.*');"
-> .|..|.dddd|.eeee|.ffff

$ perl -e "print '-> ', join '|', glob('* .*');"
-> aaaa|bbbb|cccc|.|..|.dddd|.eeee|.ffff
[download]

readdir:

$ perl -e "opendir DIR, '.'; print '->', join '|', readdir(DIR);"
->.|..|aaaa|bbbb|cccc|.dddd|.eeee|.ffff
[download]

klekker