Use the Menubar Settings->Configure Konqueror...->Enhanced Browsing or the K menu Preferences->Web Browsing->Enhanced Browsing selection to bring up the KDE Control Module Enhanced Browsing dialog box.
If the Enable Internet Keywords box is checked you can simply type normal words and phrases such as linux into the Locationbar and you will either be redirected to the appropriate site or presented with a list of possible links. To do this Konqueror submits the word(s) to www.internetkeywords.org which will redirect you if it finds a matching Internet Keyword.
The Search Fallback drop down box lets you pick a search engine that will be used if an exact Internet Keyword match isn't found. If you select None then www.internetkeywords.org will be used.
If you check the Enable Search Shortcuts box Konqueror will let you use the Shortcuts defined in the selection box to choose a particular search engine. For example you can type av:linux into the Locationbar to search for "linux" using Altavista.