I had taken this page down, since was VERY outdated, but I have decided to put something back here because more web sites than I realized were linking to it, and rather than leave you all in the dark, here is the latest General Mobile Radio System licensing information, last updated in April, 2009:
Applying for a GMRS license should be done online. The FCC's web site has come a long way over the last 5 years or so, and this is by far the best way to submit an application. I'm not even sure if they still accept paper applications. All you need is internet access, which, obviously, you already have and a method of paying the license fee such as a credit card.
You will first need to obtain a FRN if you don't have one already. You already have one if you hold or have recently held any other FCC license, or may have one under certain other conditions. If you're not asure if you have one do a search, or of you know you don't your FRN can be obtained by going to the FCC's Cores Registration Page. You can also follow the directions here to reset your password if you forgot the password to your CORES account.
Once you have obtained your FRN, you can apply for your GMRS license. This is a much simpler process than it used to be due to technological improvements at the FCC's web site. Start by going to the Online Filing link from the FCC's Wireless Telecommunications page, and login using your FRN and password. I haven't filed a license lately, so I don't know exactly what steps to follow from here, but they should be pretty straightforward. Please email me if you run into problems or have to do some tricks to get through the process (gmrs <*at* > hrdent
Assuming you meet all the the eligibility requirements, you should see you license issued within the next few business days if you look at the FCC's License Search page and search by name or FRN. Shortly afterward, you should get your paper license in the mail.
There is lots of information about GMRS online, and Google or your favorite search engine will be your friend in trying to find what you are looking for. Much of the information is old, and even a good chunk of the PRSG's web page, once a quite active advocate for GMRS, seems to have a lot of old information (last updated in 2004 as I write this). If I can help with any questions, please email me at the emai address above.
Good luck and enjoy your new license and the GMRS world!