Joomla 3.0 stable version is going to be released in the end of September but it's worth to learn the roadmap for development of Joomla 3.0 before making decision about upgrading.
Everyone who is confused by all those Joomla versions and upgrades, remember that Joomla 2.5 version is a long-term-support release (LTS) and it will be supported at least untill September 2013, so you can rely on it.
Joomla 3.0 stable version, that is expected in September, will be standard-term support (STS) release - the same as Joomla 1.6 (STS) or Joomla 1.7 (STS) .
Joomla 3.0 will be supported until 2013-04
Then, next Joomla 3.1 (STS) version will be released in March 2013-03.
And finally, Joomla 3.5 long-term-support release (LTS) is expected in 2013-09 - so it is the version that should be:
There will be about 6 months to test Joomla to eliminate any potential problems regarding security, usage, compatibility with extensions.
It's time for developers also to learn new features and prepare Joomla 3.0 templates and Joomla 3.5 extensions for customers.
We recommend to wait until Joomla 3.5 is released if you can still live without Joomla 3.0 new features :) of course to avoid struggling with potential problems.
By the way, we are going to release our first free Joomla template based on Twitter Bootstrap soon, so you can test it and report bugs.
Take a look at the infographic below:
Watch the short explaination: