I'd do it like this:
select t1.col1, t2.col2, SUM(col3),
case when [Date] = '2014-02-11' then col4 else NULL end
from my_table1 inner join my_table2 on t1.id = t2.id
where [Date] between '2014-01-01' and '2014-02-11'
group by t1.col1, t2.col2, case when [Date] = '2014-02-11' then col4 else NULL end