This is the first time I'm creating an open-source project, and I've decided (based on this question) to host it on Google Code. Now, I'm asked which of several open-source licenses I'd like to use. I'm not interested in digging into them to figure them out, so:
Which one should I pick?
You should really read about each licence and select the one that suits the most. Read and read again, to understand well. There is no other easy way to select a licence.
This question is one which is likely to result in numerous differing and quite heated answers from various camps. Some believe that the BSD / MIT license is the best way to go, others believe that the GPL is the best license.
Suffice to say it really depends on what the goals of the project are and how you feel personally about the restrictions or lack of restrictions that the license imposes on third parties.
Only you can really answer this question.
If you forced me into an answer I would most likely choose the BSD license.
Assign each one to a number on a dice and give it a roll. If you don't want to take the time to read each one and decide for yourself which one fits you best, there's really no difference between rolling a dice and using the one someone suggests for you.
From what I understand, BSD, MIT, and Apache licenses all allow another person/company to use the source code in a closed-source, commercial project, as long as they provide acknowledgement. GPL requires that any project using the code will also be released as GPL. GPL will reduce the number of people who can legally use your code, but it helps to keep improvements in the public. Those are the most important differences in my opinion. Your opinion determines which one is best for your project.
(Edit: You really should read through the licenses, though, in case "what I understand" is incorrect.)
Of course the most important consideration is to choose a license that is compatible with your project goals and philosophy. If your software is intended to be used in conjunction with some other open source software, prefer to use the same license if possible, or at least a compatible license. If you do not wish your code to be used in non-free software without your permission, prefer GPLv3 (or GPLv2). If you want your code used as widely as possible, even allowing others to distribute it under a different or closed license, prefer Apache v2 (or MIT or new BSD).
A summary of open source licenses can be found at http://en.wikipedia.org/wiki/Comparison_of_free_software_licences. Read the Wikipedia article on any license of interest to get more details. Once you have tentatively chosen one, read the license itself to ensure that there are not any surprises. If there is some part you are not comfortable with, pick a different one.