Thank you so much, I was wondering about this last night, and was really interested in the answer.yes our prayers are valid, there are hundreds of thousands of masjids around the world that dont point to the right direction not only in makkah. It doesn't mean their prayers are invalid. the Kabbah is only a focul point as to where to pray to, but if a person doesn't know where the kabbah is or the direction is not accurate then still it doesn't matter because we are not praying to the Kabbah we are only using the kabah for direction.
:salam2:
Brother Salem is right...I would like to add that..the only people who have to make sure they pray in the most correct direction of the Ka'aba are the ones in Makkah..which makes total sense..because they live there and can locate the Ka'aba's direction very easily (lucky them! *sigh* )
The responsibility of praying in the right direction falls on the imaam (prayer leader), not the people.