As you may experienced already, Joomla 1.7 has simplified much of the Joomla content work-flow, making things easier and faster to do. However, one of the things that has gotten slightly more complicated is finding and emptying the trash.
In Joomla 1.5 the article trash can be easily managed and emptied by selecting Content > Article Trash from the main menu. In Joomla 1.7, that menu item is gone but the trash feature is still there.
In the article manager, an article can be trashed by selecting its checkbox (to the left of the title) and clicking "Trash" from the row of icons at the top right. That is the same as in Joomla 1.5.
Let's say that you want to restore an article, delete an article permanently or just view the items. This is done by using the Status select box. If you click the Status select box in the row of filtering options you will see "Trashed" as one of the options. Click that.
Now you're in the Trash Manager and can empty the trash or restore articles by checking the item and choosing "Empty trash" or "Publish" respectively.