Version: 1.9 (using KDE KDE 3.5.1) When a user spellchecks a kile document, the spellchecker's language is the same as the language used defined by the last project. That can be a PitA for those users who are working on multiple projects that are written in different languages. For that I believe it would be very handy if Kile defined the language of each project. The LaTeX documents already define the language when using packaged like babel (Ex.: \usepackage[portuguese]{babel} ) and it would be nice if kile's project could define the project's language and then run kspell according to that option.
I fully agree with greatbunzinni, although I would like to have an item in the "project options" menuitem where you can select and set the language and save it in the kile-project file. This would set the default language for the spellchecker in this project. In my opinion the \usepackage option is only solving a part of the problem, because with the babel package (I'm not sure about this) you can not or it is not that easy to select for example english-us or english (united kingdom -ise) spellchecking.