Or
"in this case"
"as a consequence"

Not as colloquial as the original, I'm afraid. It's hard to find an exact equivalent in English, especially as the meaning can vary, depending on the context.

"POUR LE COUP, loc. adv. Pour cette fois-ci.
Pour le coup, il ne m'échappera pas. Je lui ai souvent pardonné ; mais, pour le coup, qu'il n'espère point de grâce. On dit de même, C'est assez, pour ce coup, pour un coup. Pour ce coup-là, pour ce coup-ci, je dois vous punir. On dit aussi À ce coup. "

http://atilf.atilf.fr/dendien/scripts/generic/cherche.exe?29...

"Familier.Pour le coup: relativement à cet événement."
http://fr.answers.com/topic/coup-22

Note that Monxmood's suggestion seems to be closer to
"Pour un coup: pour une fois." (same reference).

HTH
Flo




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Note added at 5 days (2006-09-05 19:01:54 GMT) Post-grading
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Thank you Philip. I'm not satisfied either, which is why I haven't glossed my answer. It's the sort of expression you come across all the time and you know what it means, yet you can't for the life of you work out how to say it in English! Very frustrating.
I'll keep looking and if I come up with anything more convincing, I'll let you know. It would be nice to have something to gloss, because I'm sure it will crop up again at some point.