The existing Eee PC lineup from Asus is about to get a technical refresh, with the company ceasing orders for the Eee PC 900. This is to give them preparation time for the Eee PC 901, which they intend to begin shipping within a week. With the 900 being such a relatively new model, it is speculated it was only introduced as a stop-gap due to increased competition with MSI. They didn't want to let their market share slip while preparing the Atom-based units.
This isn't the only refresh to the Eee PC line recently. Asus is apparently also planning a 10 inch Eee PC in the near future, quicker than initially expected. The rumors claim Asus was worried about MSI launching a 10 inch model as well.