I am currently testing an installation of RoundCube as a new webmail option for my company.
I will be sure to check into this myself, but does anyone know of any possible security issues that
may be present "out-of-the-box" (after the initial install and setup)? What are some common security
pitfalls that may be related to RoundCube? I would greatly appreciate any feedback. I'm looking forward
to working with the RoundCube system.

for starters, check out the issues & bugs forum. The below issue isn't a 'security flaw' IMO, but a definite issue.

http://roundcubeforum.net/forum/index.php?topic=360.0