I was asked a couple of questions during my SEO for ASP.NET Developers presentation that I didn't have an answer for at the time.
Q. What is the maximum length for the Meta Description field for a web page?
A. I've read in several places over the years that 260 (or 255) is the maximum character for the Meta Description, but that you should strive for closer to 150 characters because search engines ignore anything over that.
However, this evening I found an "official" answer on the Google Webmaster Help Google Group that was linked to from the Google Webmaster Central Blog:
Apparently it doesn't matter what the length of the Meta Description is as long as Google thinks it's relevant. One point to note, though, is that Google will only display the first 150 characters in the search results listing.
As a side note, the post that linked to above, http://googlewebmastercentral.blogspot.com/2007/09/improve-snippets-with-meta-description.html, does a great job at describing a concept that I discussed during my presentation - that the Meta Description is a great place for wordsmithing exactly what you want to be displayed in the search results. One interesting and humorous quote that stresses the point I made:
For larger database-driven sites... programmatic generation of the descriptions can be appropriate and is encouraged -- just make sure that your descriptions are not "spammy." Good descriptions are human-readable and diverse.
Q. What is the maximum length for the Page Title field for a web page?
A. While I could not find an "official" answer as good as the one above for the Meta Description field I was able to find an answer by doing a little bit of investigation of my own.
After doing some Google searches for various random terms I found that the maximum number displayed was 66 characters. I suspect that like the Meta Description there is no true maximum, but based on Google only showing 66 characters there is an effective maximum. So my advice is to try to stay under 66 characters but if you have to go over then make sure the keywords you are targeting for the page are within the first 66 so they show up in the Google listing.