Here's my fancy quoting function for Gnus.
It supports two languages (Serbian/Serbian transcription in Latin script and English), and I use the "current-group-language" as a group parameter to set the language per-group (so, for instance, gnom@prevod,org has it set to "sr", lugy@linux,org,yu set to "sr@Latn", and Gnome lists to "en").
As you might notice, I'm using local time for quoting, which makes sense since I don't want to put a timezone in the time. Also, it makes it easier to see how much time difference there was between a post and an answer (I find relative time measurements much easier, others may disagree ;).
So, no need to worry about quoting any more.