Yes, I do feel the same, way. I am expecting the PR update in the last week of this month. I am closely looking the PR update since last couple of years, although its not predicted as in the last week of December Google has updated the PR in span of just 15 days. But since then, I haven't seen much update although, few sites get update in PR but no major change. I am expecting that, we will soon see a PR update at the end of this month.
Now a days, Google PR updating monthly but it is not reflecting for all the web sites. But, for every 3 months PR updating for all the web sites. Last time, on Jan1 PR updated (3 months). I expect the next PR update will be in march end or april 1st week.
yeah.. you would never know when google PR updates exactly. I'm also expecting it in the first week of april
How will this affect our site's ranking on the SERPs? From (all of your) previous experience, will it be a dramatic change or does it have no impact ?
I would say little to no effect on SERP. It is all based on relevancy of information not just how old/how many links you may have.
On a side note, I agree with the others in here that the last week of March the next PR update will begin. You'll have to check alternate means of finding out other than the toolbar indicator.