From time to time you may hear of significant upgrades to the Linux kernel or user applications from various sources. These sources may be magazines, newsgroups, web pages, etc.
Probably the best single online resource that a Linux administrator should -- nay, must -- keep an eye on is the http://freshmeat.net/ web site. This site contains descriptions of new Open Source applications and projects, documentation, and other announcements of interest to the Linux community.
Another resource for keeping track of new applications announcements is through the comp.os.linux.announce newsgroup. This newsgroup contains postings of new applications, some kernel or application upgrades, web pages, etc. available for Linux. It is a moderated newsgroup and therefore has a high “signal to noise” ratio.
Not all product upgrade announcements are made to comp.os.linux.announce, however. Therefore, visiting the web pages or FTP sites for the applications you are using is probably a very good idea as well.