Multiplex for 1/20/2006:
Orthographical or typographical indications of intonational focus or contrast (like other aspects of intonation) are not really standardized in any writing system that I know of. In English, we variously signal intonational focus with italics (as above), with bold face, with capital letters, with paired * or # (as in "it's a Pixar film about *NASCAR*"), and sometimes in other ways as well.
Associated with this lack of orthographical standardization is exclusion from standard writing style. Because you're not supposed to use marked focus in formal writing, there's no need for a standard way to write it; the fact that there's no standard way to write it reminds us that we're not supposed to use it in writing.
It's possible, of course, that this exclusion is not an accident. Dwight Bolinger thought so; he ended "Stress and Information" (American Speech, 1958) by observing that
In short, the domains of synchrony and diachrony, of pitch accent and phonemic shape, syntax and morphology, are confused, and the analyst is tempted to become confused about them. This is an explanation, not an excuse.
However, the danger of confusion hasn't stopped linguists from working on these problems. And some of the ideas they've come up with really work pretty well. For example, in Semantic Interpretation in Generative Grammar (1972), Ray Jackendoff suggested a simple rule of interpretation for intonational focus. Informally, his idea was that if you replace the focused constituent with an appropriately-restricted variable, the resulting open sentence describes the set of things assumed to be under discussion, while the focused constituent is asserted to be a member of that set.
Applying this analysis to the cartoon case above, the first part presupposes that we're talking about the studios that might have made a film about NASCAR, and notes that Pixar is the currently relevant member of that set; and the second part presupposes that we're talking about the things that Pixar might have made a movie about, and asserts that NASCAR is the relevant set-member in this case.
There are some languages (e.g. French) where intonational focus apparently doesn't exist, at least not in the same way as in English. Instead, I'm told, speakers must use cleft constructions ("C'est X qui Y") or other re-phrasing in order to do the things that English speakers can do with intonation alone, such as to adapt a proposition in response to different possible questions, or to underline a parallel contrast.
Because I sometimes hear native speakers of French using what seems to me like intonational focus — sometimes combined with syntactic methods for signaling information structure, and sometimes not — I've wondered whether intonational focus might be stigmatized in standard spoken French, rather than completely absent. But I accept that some things that English speakers are happy to do with intonation are really impossible in French, for example focusing or contrasting prepositions or verbal auxiliaries: "It's *under* the box (not *top* of it)"; "It *was* there (but now it's gone)".
In any case, English has roughly the same periphrastic resources in this general area that French does, despite having a broader role for purely or partly prosodic methods. And on the other hand, there are languages, e.g. Hungarian, where English-like intonational focus seems to co-exist with a more central syntactic role for information structure.
In Discourse Configurational Languages (1995), Katalin Kiss observed that
languages in which topic and focus form key constituents of sentence structure, i.e. languages in which primary sentence articulation serves to express discourse-semantic functions, represent a type which is presumably as common as the language type represented by English.
But in some of these languages, the "discourse-semantic functions" are marked by special sentence positions, and in others, there are special mood-like modifications of verbs, or case-like modifications of nouns. In some such languages, similar discourse-semantic functions can (or must) also be signalled prosodically, and in others, apparently not. In languages with more-or-less free word order, ordering choices are used for similar functions, sometimes in ways that seems to represent different syntactic structures, but sometimes in ways that seem to be simply stylistic alternatives. And it's not always clear how to distinguish what Kiss calls "the (discourse-)semantic function 'topic', serving to foreground a specific individual that something will be predicated about", and "the (discourse-)semantic function 'focus', expressing identification", from somewhat vaguer notions of emphasis, novelty, or contrast. So the typological situation apparently involves many more alternatives than the four possibilities afforded by presence or absence of a structural realization of topic and of focus, and Bolinger's "explanation" remains relevant, even though we've learned a lot since 1958.