Techcrunch titles are getting longer, but I don't know if that trend stretches out to the web at large.
So I did a quick survey of my blog ( http://www.puremango.co.uk ) which has been running for 6 years.
Here is a graph of the results: http://i.imgur.com/l2iKC.png
There's a slight upward trend, but I'm certainly not seeing as direct a correlation as there is on techcrunch (but then they have more data)
So perhaps this is the result of a particular editorial style rather than a wider trend. Worth investigating though.
If you have a wordpress blog, here's the SQL I used:
SELECT post_title, post_date
FROM `wp_PREFIX_HERE_posts`
WHERE post_type = "post"
ORDER BY post_date ASC
Then I just took it into excel with the following formula to count words: =LEN(A1)-LEN(SUBSTITUTE(A1;" ";""))+1