Is there a kissing scene in Full metal Panic?

No there is not in the animated series. There is a kiss in the manga (Chidori kisses him on the cheek) and their is a full kiss in the final scene of the light novels.

http://lunablog.blog.so-net.ne.jp/2010-09-03-1

Picture located here if you want to see. Site is Japanese, just scroll down, its towards the middle.