Sorry if I wasn't clear- I know there is preclearance at Shannon, but
don't know if Aer Lingus offer it. They didn't initially when the
customs clearance was also added, and there were irate reports from
passengers wondering why the US airlines were offering it. (I think
there's a cost per passenger.) The links above aren't helpful, as they
don't make it clear which airlines offer it... and Aer LIngus only
mention it from Dublin on their website. I suppose I'll just wait and
see...

Ah, right, now I remember.

Didn't you ask this exact same question on May 15th? I pointed you at
this press release that says Aer Lingus have been using it for over a
year:

http://www.aerlingus.com/aboutus/aer...e,2012,en.html

http://www.travelbanter.com/showthread.php?t=172490

R's,
John