One new piece of functionality in SharePoint 2010 is the ability to add "Inline Editing" to a list view. When selected, this option allows for user to add or edit existing list items from the view without having to open the new or edit pages. Since this is added as part of the view, it can be referenced in any web part.
Configuring this option is as easy as modifying the list view. The screen shot below is an example of the list view options that need to be configured.
Once this is configured for the view you will see some additional icons. The add item icon will be displayed in the lower left of the view and the edit icon will be displayed whenever you hover over one of the list items.
When you select to add a new item using the inline editing, a new line item is created and you can enter the list information. Notice, that users are still presented with the dropdown options and the people picker options. They are also given the option to either Save or Cancel their changes.
Similarly, when selected the edit icon for an existing item, users will be able to do an inline edit of the item. Since this is option is associated with a view, any web part on the site that is referencing this view will be able to use this functionality. Below is a screenshot of a page that is configured to include a web part that uses the inline editing options. The first screenshot is of the page with the web part, the second is of the same page when the inline editing features are being used.