dat=datenum('17/11/2007','dd/mm/yyyy'):datenum('11/03/2008','dd/mm/yyyy');
y=cos(0.1*(1:numel(dat))); % Example
plot(dat,y)
datic=unique(datestr(dat,'mm-yyyy'),'rows')
xt=get(gca,'xtick')
xt1=linspace(min(xt), max(xt),size(datic,1))
set(gca,'xtick',xt1)
set(gca,'xticklabel',datic)