Though there aren't any embedded Linux-centric publications at the time of this writing, there are many publications that discuss the use of Linux in embedded systems as part of the other issues they cover:
The main magazine for embedded software programmers. Contains many very interesting and in-depth articles about specific issues. Subscription to this magazine is free for qualified readers. I strongly encourage you to take the time to subscribe to this publication.
The oldest of the Linux publications and the most well-established. The publishers of Linux Journal also started an Embedded Linux Journal publication that specialized in covering the use of Linux in embedded systems, but it was later discontinued. Instead, there is a regular "Embedded" section in every Linux Journal issue.
Another well-established Linux publication. Covers various aspects of Linux's use in a range of applications.
A French-language publication that provides thorough articles about various open source and free software packages. Articles often provide a lot of programming examples and tips on how to use and configure various commands and services.