When whe say 'a clamshell phone with semi-full keyboard' we would sooner think of a BlackBerry than a Nokia device. Nevertheless, it is Nokia who has introduced a device like that, that is called "Wahoo" for now on.
Nokia is probably going to face some bad days, since it had to deal with quite some leaks the last days. Recently the entire line-up for 2009 got leaked out and last week the guys of The Boy Genius had the honour to have another scoop. They are showing the first sketches of the "Nokia Wahoo", a quadband clamshell with 3.5 support (UMTS and HSDPA).

Besides the clamshell design, that is quite similar with the BlackBerry Pearl 8220, there is actually nothing that is really special about the device. According to the rumours the Wahoo supposes to go to customers of AT&T first, but when focussing on the specs the phone is probably going to reach Europe as eventually.
Source: Boy Genius Report