I suspect someone already commented on the implementation of the subj., yet I'd like to stress upon the importance of this.
When I heard Trados finally implemented this, I was really excited. However, since then my enthusiasm has wilted somehow - because Trados adds an extra line in place of each segment it merged with another one.
(I suspect it has to do with the fact it still treats EOP as end-of-segment and in order to implement this function it just copies the text from the segment I want to merge into the 'main' segment (to which I want to merge the next segment), leaving the EOP symbol as a leftover of each of this merged segment - with obvious consequence: once I've finished the translation, I have to open the translation result and remove all these extra paragraphs.
If the translation is in Word, it's not that difficult. But according to my experience the worst offenders extra EOP-wise are tables, both in Word and in InDesign (and presentations) and sometimes adding an extra paragraph into a table cell can be difficult to locate / remove (especially if you don't have the software and the client is very inept at using it.)
The competitors of SDL Trados (Wordfast Pro 5.x, Memsource Editor) managed to solve this somehow: they can merge two paragraphs together and when they do it they add a special tag; then you can simply remove it from the translation or leave it, it's your choice.
So, I would love to see something like this in Studio.