@Pablo
I'm not a lawyer, but I reckon that "offering no evidence" in the UK is probably the closest equivalent you'll find to dropping the charges in a US court. It's basically the prosecution saying "Hey guys, we don't really want to go any further with this, so we're not going to say anything, present any evidence to the court, call any witnesses, etc." From the point of view of the end result, it's exactly the same as being found Not Guilty.
The prosecution can either offer no evidence on an entire case, or if someone is accused of more than one offence, the prosecution may go ahead with the trial on some of the charges, but offer no evidence on the others. The latter situation is quite common if someone is accused of several offences where some of them are much more serious than others.
Having said all of that, I suppose a defining point about a "no evidence" submission is that - strictly speaking - it can only happen in court on the day of the trial. It is, essentially, the prosecution dropping the charges at the very last minute - actually in the court room at the beginning of the trial itself. In other cases, charges may be dropped long before they come to court, when it is usually just said that the prosecution is "not proceeding".
Back on the subject of the article itself, while I might not have any desire to read nasty stories about Girls Aloud (and I also have no desire to hear the atrocious, over-produced caterwauling that they generate and try to pass off as music) I am rather glad that legal sense has prevailed and the CPS has effectively decided to drop this one. It was a stupid case to bring in the first place and the less said about the nanny-stating poltroons and gutter-press numpties who stirred it all up in the first place the better.