No doubt there is many great changes in SharePoint 2010 over earlier versions, but some of them just come in very handy. The solutions I’m involved in at work often aggregate different information from several other SharePoint lists on the site, be it documents, contacts etc.
Lets say you have a customer list and want a customer page that shows saved documents, tasks and contacts for the selected customer. You would probably create a webpart page and add several listview webparts to that page. These list views need to be filtered so you either use one of the build in filter webparts in the Enterprise feature or you create your own. Lets say you have a querystring property called “customer” holding the name of the customer, and on the documents, tasks lists etc. have a lookup field holding the customer associated. You want a filter that makes sure only the documents for that customer is shown on you page.
This was certainly possible in SharePoint 2007, but the field you wanted to filter on had to be visible for you to be able to select it. This was a major obstacle as that information is just redundant, you have already chosen “Customer A”, why does it have to be visible for every document, task and contact on the page. It’s just stupid, and also takes up a lot of valuable page real estate.
Not to worry, enter SharePoint 2010, it now lets you select from all the fields in the list, including fields not visible in the view you have selected for your listview webpart. Thank you SharePoint 2010, you just made my job a lot easier 
