While IBM provides industry-leading ALM tools, we realize that many companies have tools from different vendors. IBM has released Rational Lifecycle Integration Adapters Standard Edition which integrate Rational ALM tools with HP ALM/Quality Center, Atlassian JIRA, and Git (including Gerrit).
I'm a member of the Design Factory for Rational ALM. The Design Factory uses information gathered from customers to design what we hope are the most useful, usable, and desirable ALM solutions on the market. We love to hear from customers that are using Rational ALM solutions and folks integrating Rational solutions with third party ALM software. Feel free to add any information on what tools (and versions) you are using and any issues you currently have on integrations as a reply to this thread.