I have a website that paginate result via jquery.ajax(). URLs looks like: website.com/index.php?page=N
I've googled and found some posts talking about it... so what i've understood is that i need to replace the "?" with "#!". It's that enought?
Besides, should i include in the sitemap a link for each page?
website.com/index.php (priority 1)
website.com/index.php#!page=2 (priority 0.9)
and so on...
Take a look to The Single Page Interface Manifesto
The best answer I can give on this is from the source, here's how Google prefers you make your AJAX content indexable: Making AJAX Applications Crawlable.
For your specific question about the URL piece, start here.
paginated results are mostly non-landingpages and do not yield much SEO traffic and/or if you have a very very big site, can even hurt your SEO efforts. if you have other ways that google reaches your landingpages (i.e.: a sitemap and/or sitemap.xml) you could skip that topic altogether.