Importance Of The Title Tag

I was reviewing my own website and wondering why the portfolio page had dropped from Page Rank 3 to grey barred, along with the system status page. Still not convinced myself why the latter changed, but the former I've worked out.

Rather annoyingly, it goes back to something I mentioned in a December Post. Then, the prices page shared the same title & description as a new page. I corrected that when I rebuilt the site over Christmas, but at the same time when I put the portfolio page into the new format page I forgot to change the title tag. As I copied the home page, the portfolio & home page share title tags. Home page dropped 1 page rank, portfolio page dropped all together.

That really does spell out the importance of keeping these little lines different. The ones that were the same until December are now both back up to PR3. I just need to see why the system status page is also grey barred, when that was PR4 before the update.

It's documented that this tag shouldn't be excessively long, 66 characters is about all that Google displays, so keep within that. But in this case it was only 13 characters, so I was wondering if there is a minimum limit as well? That's hard to work out and prove. So plenty for me to be looking at over the next couple of weeks!