Mira esta solución, espero te sea de utilidad.
Código SQL
[-]Create table #tblog(
Logdate datetime,
mediatype Char(1)
)
insert #tblog values('09/11/2012 09:18:22', 'A')
insert #tblog values('09/11/2012 09:26:10', 'A')
insert #tblog values('09/11/2012 09:35:00', 'B')
insert #tblog values('09/11/2012 10:34:25', 'B')
insert #tblog values('09/11/2012 12:55:31', 'A')
Select datepart(hh, Logdate) hora, Sum(Case when mediatype = 'A' then 1 else 0 end) mediatype_A,
Sum(Case when mediatype = 'B' then 1 else 0 end) mediatype_B
from #tblog
group by datepart(hh, Logdate)
drop table #tblog
Salu2