Series or Seasons.
Where does your allegiance lie?
Series or Seasons
Series for UK series, seasons for US seasons 
It mainly comes into play when I'm discussing DVD/Boxsets. Most of the time it's series for me.
As most UK series barely stretch more then 6 episodes, it seems kind of laughable to call them seasons.
Whereas most US shows get 22-24 week runs, so being nearly six months of scheduling, does indeed cover a weather season (or two).
I don't know how Coronation Street is measured, probably some sort of geological term.
The Cobble Age?
Quote: Leevil @ April 21 2009, 6:51 PM BSTSeries for UK series, seasons for US seasons
Yeah, same with me. Or if I'm speaking with mainly British people (on BSG, for example), I'll use 'series', but if I'm on YouTube I'll go for 'seasons'
Quote: Leevil @ April 21 2009, 6:51 PM BSTSeries for UK series, seasons for US seasons
Ditto.
It actually really bugs me when people refer to a series as a season. And it's often specific types of person who I won't mention on here. (And no, I don't mean: blacks, gays, Frenchies, asians, lesbians, the mentally handicapped (well...), or otherwise physically disabled.)
What about socialists?
Quote: Leevil @ April 21 2009, 8:56 PM BSTWhat about socialists?
I already excluded the mentally disabled.
Ah, I see. 
Series, definitely. I know the Septics call them seasons but it shouldn't be encouraged - they already use enough wrong words for things.
I always called a serialized set of television shows a series, until I started doing jobs that required the use of American English, including the American spelling of series, which is season. Season is becoming increasingly in vogue in Australia, especially on DVD sets of TV series.
From Wikipedia: North Americans call a short run lasting less than a year a season; People of the United Kingdom and the Republic of Ireland call this a series. This season or series usually consists of 6–26 installments in the USA, but in the UK there is no defined length. U.S. industry practice tends to favor longer seasons than those of some other countries.
What's the attitude toward the spelling of 'programme' in the UK these days? Is 'program' ever acceptable? When I was at university, 'programme' was de rigueur in Australia; now it has largely been dropped in favor of 'program'.
Television programmes, programmes of activities, and computer programs.
Afinkawan's spot on.
Has to be a series
In my view 'Season' is any show that runs for 13 weeks or more... so it's not necessarily an American thing, it just happens most American programmes are longer. My Family / Two Pints are examples of UK shows that has run for 13 episodes in a go.
If I've used 'series' twice in a sentence I sometimes replace the second with 'season' just so it reads easier.