I think it's important here to differentiate between fingerprints and palm prints. For fingerprint matching, a high level of resolution detail is required, in order to identify and compare the loops and whorls. But for palm print matching, one is looking not at this fine level of detail, but rather at the creases and lines in the palm. If you look at your own palm, you'll easily see the pattern of lines on the palm (think palm reading!), but you won't be able to see the detail of your own fingerprint.
Take a look at this photograph. It's of a hand print lifted off nylon fabric:
[qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_4023754929fc343b15.jpg[/qimg]
http://www.sciencedaily.com/releases/2011/01/110131073141.htm
While this print was lifted using a new technique (developed in 2011), you can easily see how sufficient detail of palm line patterns is left on woven fabric. Note also how it appears extremely hard to see fingerprint detail on this image - that's why it's always been deemed near-impossible to life usable
fingerprints off woven fabric (though this new technique claims to make it possible in some cases).
And that's why I think it's plausible that the police were able to lift a usable palm print from that woven cotton pillow case, and that there was sufficient detail of the lines and creases of the palm to enable a match to be made to Guede. There's a very significant difference between the resolution/detail required for a palm print match than that required for a fingerprint match.