If yes, what precautions should I take?
With an MIT/X11-licensed product:


you CAN:

re-use the code freely for your own use,
re-use the code freely for non-commercial AND commercial re-distribution, whether in source or binary form.

you CANNOT:

claim authorship of the software,
thus you cannot attack the original author for using or publishing his original version.



So, yes, you CAN use MIT/X11-licensed plug-ins in your commercial application.

MIT/X11 is basically a simple contract that says:


Person or company X created Y.
Y belongs to X, but X is granting you the right to use it and do whatever you want with it.
X cannot be held accountable for anything that goes downhill with what you do with Y.

