Apple has not confirmed any keynotes at this time, but that does`t mean than one isn`t right around the corner. Apple has in fact been acting a bit strange lately and have skipped the keynotes they normally have in February and March. They are, with other words, taking a big keynote break.
So, in terms of the next keynote, I will expect it to be in June sometime. Probably the WWDC event, where Apple presents new software including iOSX and iOS. More accurately 10 June 2014 (not confirmed by Apple), if we choose to believe wheniskeynote.com. Maybe forward slash hopefully they will surprise us with a keynote before that, until then we will stick to the WWDC to be the next keynote.
Baaaam