An imam must choose very carefully what he says from the mimbar.
the majority of ppl listen very attentivily.
talking about current issues from the mimbar every week can very easily label an imam as an extremist type, thus putting the reputation of the masjid and all musallees who attend there at risk.
Sure, mentioning them once in a while maybe in the form of a dua is fine.
e.g. "..........and may Allah (s.w.t.) help our muslim brethen in Iraq/Palestine etc who are going through a very testing time. may allah strengthen their iman and safeguard them against all evils. ameen......"
something like that would be fine.
also mentioning masjid aqsa in the dua of the second khutba is also very benificial.
the best thing for an imam to talk about on fridays are things which would
make us all better muslims,
improving our akhlaaq and aadaab (manners),
teaching us to be model muslims,
being tolerant,
and to instill the sunnah and love of our prophet (s.a.w.) more into our hearts.
Alhamdolillah, we, in our local mosque, are very lucky to have an imam who talks on these things aswell as talking about all major events and festivals that occur throughout the year(islamic and non-islamic) at the correct times.
e.g. xmas at xmas time, easter, mothers and fathers day, bonfire night, muharram (aashura), shabe e baraat, etc etc.