Lego is going eCommerce on bricks properly at last! Although you have been able to order Lego sets online for some time, as well as early Lego Factory, it was still not quite ready for you to design a set and have the parts delivered.
Lego factory at first seemed extremely promising, until it was discovered by users that one model may actually pull in bricks from 6 or 7 standard bags, and that you would have to pay for the whole of each bag even if only one piece was used - these bag palettes were quickly figured out, and users learned to model economically in them.
Lego has recently revised the system, and made it more flexible, with more bricks to choose from, and has now individual by-part pricing instead of bag pricing. The palette is not the complete range, and does not include sophisticated elements like Technic or space parts, but mostly the simple bricks. However it is growing, and this has the interesting feeling of full on user-created-content. It is approaching the point where you can design your excellent Lego model (which you may have modelled before using LDraw CAD), and then upload it to Lego to get your design sent to you, as well as sharing that with others. If the wealth of models and sets that people on Lugnet and BrickShelf come up with started to see representation, Lego could suddenly get a huge boost in possibilities.
Personally, I cant wait for most of the full range to get included, especially the Technic side of things with gears, axles, and pins.