I don't think Google is case sensitive so it wouldn't matter. Try inputting "KEYWORD" and "KeyWoRd" and "keyword" ... they all come up with the same results.
As for a human, I always think of "shouting" when I see all caps, so I personally wouldn't use them.
I believe chopin is right - capitalizing has no offect on the search engines - but it does have an effect on users.
That effect is generally negative in my opinion. Nobody wants to be shouted at, and the title shouting at you only makes you expect that the website will shout at you too.
Most search engines already boldface the keywords in your title tag that were part of the user search - that is sufficient for users to scan for what they want.
Surely it is spelt "capitalise"
Agree with chopin - capitalized titles give a negative impression. And I wonder wouldn't they affect being listed in DMOZ - they forbade capitalized titles in their page listings, so they could also dislike it in page meta title.
Anyway, having good snippet is now more important than just a position in SERPs, obviously you have to be in first 10, but good snippet can give you more than #2 or #3. And if you want to know what good snippet is, try googling for something yourself. I search for everything in G everyday and have no doubt it's not just a matter of eyecatching.
Eyecatching is needed if you put adds in material someone reads not bothering for adds. SERPs are different - searcher reads it, and looks for snippet assuring them they'll find what they want, so they need to show you're relevant.
If I'm not mistaken, the original PageRank patent does mention a flag that is set when indexing words on a web page which indicates if the first letter of a word is capitalized. The assumption is that a capitalized word should be given more weight on a page. This probably would not apply if the entire word was capitalized. Also mentioned was a flag indicating if a word was in bold, and the font size of the word relative to the other words on the page.
I think the algo can also add some points to words entirely capitalized, especially if the rest of the paragraph is not, but it's not entirely the point of getting more and more points in the algo. If your snippet apears like V14GRA CH34P FL1GHTS spam, people won't click on it even if it were Google #1. And if your content is not useful without capitalizing, you'll hardly get natural backlinks.
I am so sick of the google Dmoz thing, I know that if I applied under 1,000 different allias names that one of them would be accepted for some low ranking category, then once in I could move around after a while, but who wants to wait?
Any editors out there? That would be willing to consider adding my site to dmoz for me? it could be financially benefitial for you.