They're used to it
They've been using lasers from the observatories in the canaries for some time now,
such as from the Isaac Newton telescope there:
http://www.google.com/imgres?hl=en&gbv=2&biw=963&bih=1333&tbm=isch&tbnid=Y7HiBM7RsAT-YM:&imgrefurl=http://www.ing.iac.es/PR/press/ing42007.html&docid=CxcUhwxa7vz8NM&imgurl=http://www.ing.iac.es/PR/press/glas1.jpg&w=1000&h=878&ei=rfPVTpmHHIqYhQeL4JB9&zoom=1
The lasers are used to create an "artificial star" in the field of view of the telescope by fluorescing sodium atoms in the upper atmosphere (you need a bright star in the image to align the optics with).
Newer telescope plans have lots of laser stars (10-20) and beams, e.g. for the EELT (42m) telescope that ESO is building.