They have different sizes to others atm 80 and 160GB are their main MLC varients.
check out some reviews of the new Crucial C300 SSD that comes in 128 or 256GB sizes.
It is a lot faster than the Intel and due out for sale on the 22nd of this month
The X25-E is SLC, and comes in 32 and 64GB, so 128GB would be a logical size increase. As for when it will come out? Probably not soon, if at all. SLC is lower density than MLC, and it is more difficult and expensive to use it for large drives.