M. Son of the Century (Soundtrack by Tom Rowlands)

[Stefan]

It's just a few seconds but they get me excited for the soundtrack! Hopefully it will have its own release.
Has this ever been done for a series OST?

[ThePumisher]

Has this ever been done for a series OST?

Heroes got one (including the Chems)
Twin Peaks got one
Not sure about Misfits, but i remember they made a tracklist on the E4 homepage for every episode

[Enjoyed]

Has this ever been done for a series OST?

All the time!

Some great ones that come to mind are the Cristobal Tapia de Veer soundtracks to both seasons of Utopia.
The Green Wing soundtrack, by Trellis.
And the Spaced soundtrack!

[Bosco]

I feel like we are confusing OST with scores. 

To answer the question though about TV series coinciding with a successful music release, S U R V I V E did really well with the Stranger Things score. 

I wouldn't expect a physical release from this but if we are lucky, maybe a digital release of music featured in the series?

[Stefan]

I wasn't aware that there's a difference between OST and score, so thanks, another thing learned

Physical release would be awesome, but I'm happy about any form that lets us listen to what is teased in the trailer

[Bosco]

I wasn't aware that there's a difference between OST and score, so thanks, another thing learned

Physical release would be awesome, but I'm happy about any form that lets us listen to what is teased in the trailer

The confusing part is OSTs can also be Scores, or at least include original composed music for film/tv/etc... I think it might be a marketing thing, because the word "score" doesn't necessarily roll off the tongue and isn't a universal layman's word like soundtrack.

For instance:

Hey man, did you check out the new Stranger Things Score?
Hey man, did you check out the new Stranger Things Soundtrack?