I'm a long-time Delphi programmer and relatively recent migrant to Linux. This book absolutely fills the gaps for me in the numerous places where I'm asking "Now, how the heck do I go about doing THIS on Linux?".
It's not about Kylix (although the samples and solutions are in ObjectPascal, of course) so much as about accessing the nuts and bolts of Linux through HLL calls to the OS, MMS and filesystem. Although it is primarily relevant to ObjectPascal it will be a great resource for developers using other HLLs on Linux too. It really fills in the bits that are missing from Linux books, programming books, FAQ forums and so on if your history has been with DOS and Windows and, especially, if you want to cross-plat your Delphi components.
I needed this book a year ago and I'm overjoyed to have it, now that I'm using Kylix 2.