PR 1 to PR 3 - How Big a Deal Is It?

In terms of actual authority, this is a great step. Especially if it jumped 2 spots on 1 PR update.... I've noticed with many personal sites that this happens twice. So if you keep up the work, it can possibly jump to PR5 the next update (but of course, this is harder).
Overall, it simply worth a LOT more, and this tells you you are headed in the right direction.
A quick glance at the PRO's:
Your site has gained more authority. It is now harder to outrank major and inner pages on your site.
Your site has more value in terms of backlinks. A backlink placed on your homepage easily has 3 to 10 times more value then a PR1 link.
Your site is now simply more valuable. If selling on Flippa, it can sell for twice as more, easily.
New pages made will now automatically be indexed faster. Chances are, if it is a forum, a "permanent" google bot is now in place.
Less backlinks now required, (as well as less SEO) to rank for more keywords/ terms.
If competing for many, many keywords, it should slightly jump upwards for many of them (though this is not necessarily the case).
CON's:
There really aren't any.
Congrats!

George,
Backlinking Expert

Well done ...

It's definitely better than the other way round!

It might help your site to rank a little higher for some keywords. It's certainly no panacea, though (as can be seen from the regularity with which lower-PR pages outrank higher-PR pages in Google's SERP's).

Of course, strictly speaking, websites don't actually "have page rank" at all: only pages have page rank. But I'm guessing that you're referring to your site's home page, or landing page?

I think all my niche sites' landing pages are now PR-3 or higher, so I ought to be able to tell you what a wonderful thing it is, but I suspect the reality is that it may make less difference to anything than you expect.

Certainly the overall impression one gets of "what Google's up to" these days (including impressions gleaned from what they tell us openly) is that relevance matters more and more and page ranks matter less and less.

My guess, though, is that there might be some not-fiercely-competitive keywords for which your site may possibly now rank a little faster than it would have done without this happening. And it's a move in the right direction, anyway. And links from your home page (i.e. to other pages on your site, and/or to other sites you own) are now worth more (though, again, that's far more context-relevance-dependent than page-rank-dependent).

It's also even possible (though hardly relevant to most people, admittedly!) that new material on your site might be indexed a few hours more quickly than it would have been before - just a small "technical benefit" there.

Page ranks, I believe, were last updated about 4 months ago (unless this is something new today?) ... and the previous update was in April 2010, so they do seem to be pretty sporadic ... but the factors affecting sites' rankings in the SERP's can of course change all the time, without formal PR's, per se, necessarily changing at all.

Hey Ken, Well done. My site has also gone from pr0 to Pr 3! So looks like were both in luck!

Also I believe that google updated the page ranking only today..

Yeah, Google updated its PR today. I had one jump to PR3 and another to PR4, then a bunch to PR2/1. I don't think PR on its own means much at all, but it is still a good indicator of progress and a solid way to benchmark your site. That said, PR on its own doesn't matter much.

Hi

My biggest point would be to say that when you are doing your search engine optimisation on your page rank of 3 it will take a lot less time to get its position on google.

so say if a keyword normally takes you 6 weeks you will achieve it now in 2.