Google works in mysterious ways a lot of the time, but it does take time for the PR to change after the work has been done.
For increasing the page rank of any website, you have to put attractive content in your website and get quality link from high pr websites through link exchange as 3 way or 2 way, so definately i can say u will see the improvement.
The Google Toolbar is updated approximately 5 times a year, so often shows out of date values. It was last updated on 13/14 February 2010.. Source: wikipedia
That is Good. I was lucky that all of mine went up, there was a time last year where they were going down. Some how I must be in favor by Google, as all of my websites increased