There's some testing doing the rounds at the moment which suggests that Google will only index (i.e. use for textual evaluation) 12 words from a title element. That's a fairly long title.
But generally, I would suggest that there is definitely a 'too long'. Titles are intended to give a quick snapshot of a page's content, before a user actually clicks through - i.e. when they are not on the site itself.
Because of this, most places that display a title will restrict that display to a certain number of characters. So, too many characters or words will make your titles not fit for purpose.
If you rely on a third party like Google to snip the titles you use, you lose control over your site's display - which could be the difference between getting the clicks you're after and being passed over in favour of a more attractive listing.
Next door at That Other Search Engine, there's a section of WMT that will sing out if your title is either too long or too short. Ditto for the description.
Don't know what the "too long" cutoff for titles is, but they objected to three letters (one perfectly normal word) as too short.
In the case of titles, please remember that humans will see them. Any title will have to be slightly truncated if it's enormously long; it can be massively truncated if the user is in tabs.
:: further drifting ::
This is food for cross-browser comparison. I know I once checked behavior with tabs-- it's somewhere in the bowels of the CSS forum-- but full-page titles are interesting in their own right. My current browser will cut a piece out of the middle of the title if it doesn't fit. (You don't need to look for a long title. Just scrunch down your current window.) Do they all do it that way? No idea.
The current title tag contains three pieces of information in approved inverse-pyramid order: First the thread title. Then the forum title. Then the overall "at WebmasterWorld". This is appropriate for right-end truncation. If titles normally get chopped in the middle, your order of importance would be better off as left-right-middle-- in that order.
Leading inevitably to... Would g### be happier if this thread had a shorter title? Is "Long title OK?" preferable to "Long title tags OK?" When do you cross the line to the corresponding offense of "Title too short"?
After getting hit with WMT 800+ "titles duplicated" because once upon a time we placed the short title of the news column in every periodic title, we switched to putting a relatively LONG title (as much as 1000 char) with the most important part carefully framed in the first 60 chars (which is what G displays). Then we rearrange the next most important parts to show up in the first 130-146 of the description with again up to 1000 chars (headlines) in the description. That way if/when G/B/Y change their minds again, we should be set without change. Not sure it is any better than any other method, but G sure likes our photos on those pages.
Test it - there is a sweet spot both for Google and your users. Google is not your enemy on this, trust me, please. The title needs to give users a quick and sweet summary of your page's theme or topic, not a wish list of every keyword you want it to rank for.
That's been my experience, but I haven't tested it enough to say for sure. And that's why I asked people to please test it for themselves.
It's been several years since I saw a page rank high for a phrase that was buried in a long title tag, except for VERY low competition phrases. And I can't imagine that those phrases really needed to be in the title tag, given how sensitive relevance is these days.
Meta description can be a good bit longer - around 160 to even 200 or so. That gives Google a bit of choice to pick various snippets from in different situations. As long as your meta description is representative of the page, I find that even when Google chooses to truncate it, they use it or its parts a lot - and appropriately for the most part.
Google still will manufacture their own snippet if you rank for a term that really is outside your meta description. However, even in those cases, I find the snippets to be pretty effective.
H1 length is not an issue at all, as far as I know (it's also not as much of a ranking factor as it used to be.)
[edited by: tedster at 1:18 pm (utc) on Jul 6, 2012]
I keep my titles to a maximum of 69 characters, although I have seen them truncated at a lower character limit. For the meta description I use a limit of 156 characters. H1s should be short, i.e. no more than 3-4 words.
I believe I have occasionally, in the last few months, seen our pages come up for terms/phrases buried in our "1000+ char" title and description.
The situation for these pages, is a weekly current news column by one author which covers, sometimes, over a dozen very related topics. Each multi-paragraph topic has a headline title (typically 5-9 words). Previously we used to put the name of the column alone in the title and the date and topic headlines in the description. Since G NOW wants unique titles, we've gone back and copied the full description into the title (following a much shortened version of the original column title) and rearranged them when needed so that the most important headline fills the first 60 chars.
"the current title tag contains three pieces of information in approved inverse-pyramid order: First the thread title. Then the forum title. Then the overall "at WebmasterWorld". "
Yes, but notice if there are multiple pages of comments, that all the subsequent pages have exactly the same title... tsk,tsk!