Since you opted to resurrect this thread, let me add:

Modern SSDs like Intel X25-M use a trick to get high random write speeds. When defragmenting, it will overwrite existing data. For example, it will put the most used applications at the beginning of the disk, as that's where HDDs are faster. But in reality, the Intel SSD has remapped the locations to free flash cells in order to get higher performance.

So what windows thinks is the beginning of the disk, may be somewhere in the middle. The SSD is silently moving data to other flash cells without Windows or anything else ever knowing. Now here comes the trick: it has to remember where all these 'mappings' correspond to. For every I/O this 'list' needs to be referenced, to see where the data really is being stored. But with defragmenting this list can grow enormously, and this starts to hamper performance. To remedy, all sectors need to be zero-written again, or using a special utility to wipe the special flash cells on Intel SSDs.

So if you defragment, this 'list' is getting filled up and can slowdown performance significantly. So defragmenting can actually be very harmful to performance. So there should be no reason to do it.