Just to chime in to this subject. (I haven't had this problem... yet. Fingers crossed.)

Nokia should handle this like Canon did fix my camera few years back: There was a known issue on certain camera model where some cable become detached from a CCD, causing malfunction. That was covered under warranty regardless of the age of the unit. I sent my camera for repair when it was ~3 years old, well beyond the normal warranty period of 1 year. They paid all the shipping back and forth, and were quick too. I think it took about a week for the whole process! This is how do you handle design issues in your products to keep your customers happy and coming back in the future.

Second thing... I think there is a possibility to "prove" the design in N900 is faulty. I'd start by making some calculations showing the shear force to the solder pads using the measured insertion/removal forces of the supplied USB cables (charger and data cables). Solder land sizes should be possible to find from the connector datasheet. Looking at the USB connector size I don't think the pads are large enough to keep the shear force below some industry approved/recommended shear force for solder joints. (I'm guessing here... but I'd be surprised if I'm completely off with my statement. Just look at the number of people having this issue!)

Third, since the connector is intented to be inserted by hand, there must be some tolerance designed in if someone insert the plug not exactly straight, or remove it not pulling it out exactly straight. Don't ya agree?