Drupal 7 only wrote 40 critical errors at this time, which means it is pretty close to rc-1. This means that Drupal 7 is not so unstable, APIs must be in place, etc. Therefore, you should not expect any major changes from now on, only bug fixes, etc.
This does not mean that you should use Drupal 7 for production sites, but you can actually, if you are not doing fancy things, etc. So you can start learning Drupal with Drupal 7.
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