PS3 News reports that Sony has slipped two new PS3 Slim models though the FCC under its old pseudonym Sand Dollar Enterprises. The new models are labeled as the CECH-2101A and CECH-2101B and as far as we know, the only difference between the two is HDD type.
Unfortunately, it doesn't look like Sony has plans for a specs bump for the PS3 Slim just yet. PS3 News reports that the wireless specs on the "new" PS3 Slims include 802.11 b/g and Bluetooth, identical to the current models. The site goes on to speculate that the filing could just be because Sony found a new manufacturer for some of its wireless components, and was forced to pass the PS3 Slim through the FCC again.
Still, it's nice to dream of an upgrade.