Common Travel Area/Dublin Question

When I moved to England a couple months ago, I was told I couldn't go through Dublin because I wouldn't be able to establish on my visa/passport when I actually entered the UK because of this whole common travel area thing. My question is this:

My sister is getting married at the end of May. Aer Lingus, which goes through Dublin, is undoubtedly the cheapest airline, and we're on a tight budget. Does the common travel area thing still apply after my initial entrance in to the uk? Am I now okay to travel through Dublin when coming back to the UK, or do I still need to avoid it?

HELP!!

If you already have a visa for the UK that has been validated then yes, you can travel through Dublin. Just make sure that if you're applying for Naturalisation that you keep records of your travel (like your boarding cards) because you will not receive entry stamps from the US as a US Citizen and you won't get an entry stamp from the UK either because you will not pass through UK Immigration.

Thanks WebyJ. You just eased A LOT of tension with that answer! I came through Heathrow when I moved here, so I got my initial UK entrance stamp thingy. So... PHEW! Thanks again!

Just a teensy quibble about terminology here: spouse visas don't actually need to be "validated."  If someone enters through Dublin mistakenly, as I did, their visa is still valid, they just have to either channel hop or make sure they take particular pains to establish proof that they were in the UK soon after their entry.  I just don't want anyone to read this and flip out, thinking that their visa isn't valid and they're in the country illegally .

Actually, she will receive entry stamps from US immigration. They will either get off the plane in Dublin and go through US immigration in Dublin airport before reboarding for the flight to the US, or they will just go through US immigration in the US like all other international flights into the US.