I've looked athe bug that Tassilo submitted, and can see the problem.
It occurs when the name of the symlink differs from the name of the file
pointed to. e.g. if I do

ln -s teach txt/org/teaching.org

Then if I have previously visited the file as 'teach', Emacs opens it as
'teach', rather than 'teaching.org'

When iswitchb opens teach, it uses find-file-noselect, which opens the
file 'teaching.org' with that name as the buffer, rather than using the
name 'teach'.  The fix then is to tell iswitchb to use the name returned
by find-file-noselect.  I've attached a new version of the function
iswitchb-read-buffer - please can you test it to see that it solves the
problem for you Tassilo, and then I'll commit a patch.  I guess the only
issue is whether the buffer should be called the name of the symlink
'teach' or the name of the real file 'teaching.org' - is there a way to
tell Emacs to prefer the symlink name?

Thanks for the report -- I didn't even follow the recentf code in
iswitchb, it was contributed by someone else.

Stephen