SharePoint 2010 makes it easy for you to host multiple Site Collections within a single Web Application. In terms of Internet-facing websites this capability is extremely powerful when it comes to hosting mini-sites. And although they all might use the same credential store, they might need a login page using their own branding. Find out how to configure different login page for every Site Collection in a single Web Application.
If you have deployed SharePoint Packages in the past, you know, that, unless you have a second farm, deploying SharePoint Packages means outage to your Web Applications. There are however a few things that you can control to minimize the impact on the availability of your websites.