The KDE application standard search – the one you can call by pressing ctrl+f inside of an application – is horrible. Other solutions (like Shift+/, the google toolbar in konqueror) are barely known and not fulfilling usability needs. For these reasons there is a popular bug report to give a Firefox-like search to all KDE application- like konversation has it already (screenshot).
Now kate also implemented such a search bar – it looks like the idea spreads among KDE developers, and gets into their heads (if you follow the bug discussion you see that many developers do not feel comfortable with such a search bar, I do not really understand why, though). I hope it will become a standard function in KDE which can be called from any KDE application to easily find text everywhere in the same way. I think for application developers it would not make any big difference because I guess the search is implemented as a standard function – and for users it would mean a huge improvement in usability, because finally the search field is not blocking the scanned text any more.
Ah, and: if you want to support this new kind of search bar, vote for it, tell the konversation and kate developers that you like their work, and check if you can help somewhere to implement it as a standard function for KDE 4.