WordPress Web Hosting
WordPress hosting is available from almost every web host out there. If your host offers C-panel access then you will probably be able to install your wordpress site with just a few clicks.
You will use one MYSQL database for each WordPress domain that you host on your site.
BEFORE you purchase web hosting check this out.
As of 11/10/2010 there are a few hosts that offer unlimited domains and unlimited MYSQL databases with their basic service.
Hostgator, Host Monster and FatCow all offer unlimited MYSQL databases.
Bluehost offers 100 databases. I have had my sites hosted on Bluehost for several years with very few problems. I have used customer support and they have always been knowledgeable and helpful and they usually answer the phone within one minute.
Unlimited Domain Hosting
Remember Unlimited Domain hosting is not the same thing. You will want to get a hosting account with Unlimited MYSQL Databases. Often you will have to look around on the site to figure out how many databases come with the program. For instance GoDaddy only gives you 25 MYSQL databases with their hosting plan.