It seems as if they've already released a fairly simple plugin to integrate Bitbucket with JIRA, which is nice. I'd personally like to see deeper integration between Bitbucket and Atlassian products like Crucible, JIRA, Confluence, etc.
Although I can see the many possible integrations between Crucible, JIRA and BitBucket, I'd love to hear if you have any thoughts on Confluence and BitBucket integration. Right now you can quickly view the contents of a BitBucket repo from a Confluence page: https://plugins.atlassian.com/plugin/details/40188
Could it be that if they might use Bitbucket as an entry point to their products? Perhaps with more integration.