The current GPLv2 will accomplish your goals, and prevent anyone from taking the source code private. You may have to wait a long time for GPLv3, so go ahead with v2 now. As long as you own the code copyright or have the consent of the copyright holders, you can always re-license under version 3 when/if it appears. If you have specific needs that GPLv2 does not satisfy, then you might have to pick another license.
There is considerable value in the GPL because it is well-known and many developers will not work under other licenses.
This was first published in January 2007