I'm from Scotland and I love reading about all the differences in wedding's between here and overseas.  

I'm prepared to stand corrected by other UK bakers but one difference is that we normally don't have a Groom's cake, what is that?  I know it's obviously for the Groom but is it in addition to the Wedding cake, is it served at the wedding?

Also, what is the "normal" format for weddings?  We usually have the ceremony (whether Religious or non Religious), then on to the venue, if it's in a different place to the ceremony).  This is normally when the Wedding party go away to have photo's taken and the guests hang about chatting, having a drink and some nibbles.  When the party comes back it's time for the cake cutting, speeches and then dinner although the cake cutting can be after dinner as well.  Then the reception where the Bride and Groom have their first dance and when additional guests come to join in and party with everyone.

Is this pretty standard everywhere?

The sequence of events you have described is fairly standard in the USA, as well.  Yes, the groom's cake is in addition to the wedding cake and is often a different flavor to give guests a choice or is a favorite of the groom.  While wedding cakes are usually quite formal, the groom's cakes are usually fun and playful, reflecting something with special meaning to the groom, such as a hunting cake, a truck cake or a dragon, etc.  It is a way to honor the man, who is often overlooked in the elaborate preparation for the wedding.

Exactly

Is the cake normally put out for a dessert?  We usually put it out along with the evening buffet.

We do the same.

The groom's cake is not for all of the United States, maybe more southern? I don't know, but we don't have them where I live. I've never been to a wedding with one nor have I had an order for one.

I think the groom's cake is more of a Southern thing. Growing up in Georgia, all my relatives that got married all had a groom's cake, usually chocolate.  But, after moving to CA, I've never seen one, and a lot of people had never heard of that. And I've never been asked to make one. 

Oh I've done some here in CA.  And a few when I was in IN too :)  Not wildly popular but some......

Maybe it is primarily a southern tradition.  Almost every wedding here, middle Tennessee, large or small, has a groom's cake.

Northern Ohio - I've never been asked to make one, nor been to a wedding with a groom's cake.  I did watch Steal Magnolia's, though :)

I've never done a grooms cake here (in Canada.) Is it a fairly newish tradition? Some of the ones I've seen are very creative!

Apart from that, it's more or less the same ole traditions here too :)

My son-in-law, who was career Airforce, had a fighter jet (made by my sister) as his groom's cake 32 years ago.  Been a "southern" thing for a long time, lol.

No, it's not new....I did some as long as 25(+/-) yrs ago.  Here in CA there are not all that popular but I bet I've done more than a dozen over the yrs.