britchick, rukhsati's are cultural "giving away of the bride" ceremonies, not religious. once the nikah's is over, thats it, you're married and can live together and all of that. i suppose it makes sense to separate them if the bride and groom are in different countries and its not possible to have them physically present, together, on the same day. i know people who've had phone nikkah's because the groom wasn't able to join his wife in the same country for whatever reason and then he's flown over for the rukhsati, but i found that whole concept silly. immigration will happen whether its now, 6 months later, or a year later... more and more, the "jald baazi" of a nikah ticks me off. its like stoppit said, people say "its just a nikah", lets do it before dinner some night and get it out of the way so papers can be filed.
I guess they do it beacuse people want to go home with their spouse after the wedding and not sit at home or worse at the in laws with no hubby. I have seen people wait for 2-5 years even for the immigration to take place.