Ok, I know that at least some of this must have come out before, and I can even vaguely remember a particular instance or two... but I would like to put it straight: some forums, and I mean even phpBB(-like) ones allow quoting of posts by means of special tags. Personally the style I prefer most is the same as that applied by some mail clients when displaying HTML formatted mail: with a css-built thick line on the left and some amount of indentation. Granted, often those other forums are not hierarchical and they benefit from such a beast - and quite funnily often people there don't use it at all! But even here people, who generally put much more care in their writings, like to quote relevant parts of posts they're replying to. Personally I like to use <blockquote><i>...</i></blockquote> for this. But then I'm sometimes in difficulty when I have to also insert a random quotation for which I don't see many alternatives to using <blockquote> tags again...

Again, when quoting, whatever style you choose, you have the original node to copy from: I just do so, and if the amount of ad hoc formatting is not too much, I reproduce it by hand, e.g. by inserting a bunch of <c> tags or a pair of square parens around a monk's name. Alternatively one can select the text and use FF's "view selection source"... however in that case one would find e.g. links rendered in HTML rather than in PM's (internal) shortcut form. OTOH to overcome this one can switch to the XML view of the original node, which actually exposes the source of it, with the only disadvantage of being a few clicks away.

Now I wonder if:

1. the source of the node being replied to could be displayed in addition or instead of the rendered one, upon a user preference, of course - this could be a problem only if such a source were considered "private", but it is in fact available from the XML view mentioned above;
2. an official tag for quoting could be implemented, with a reasonable default, but customizable via css, like quite about everything at the monastery.
3. a quote button could be also/alternatively implemented, that would put the whole node source in between such quote tags.

Incidentally, in use Perl; which is based on slashcode and is in many ways poorer than PerlMonks e.g. wrt internal and external linking shortcuts, the last two features are now available if you accept to try the new experimental slashdot discussion system, with a nice quoting style of the type hinted to above.