OK, here is my 2 cents worth. First, can the block be resolved with some discussion of the other affected parties? Sometimes just talking to people will work wonders. Sometimes people aren't aware they are causing a work stopage for someone else. Sometimes, you need to go higher in the chain of command to get someone to understand that your work is higher priority and needs to happen first or the task they need to do for you needs to move higher in their priority list.
Next, what else can you do until the circumstances clear. Well what tasks are not on the critical path for that particular change? If I can't put this change on QA right now can I work on getting this other task done instead and then loading both to QA together? In many way the most important part of this when you are blocked is to look for what isn't on the critical path of the blocked task. Just because I can't move an SSIS package to QA right now doesn't mean I can't work on an SSRS report. Can you get code reviews within your team done in the meantime or write unit tests for the next chunk of work (or unit tests to cover existing code if you don't already have a full suite of tests)? Do you have a dev who is behind on some other tasks and could use some help in the short term? Can you do a little pair programming in that case?
What can you do to help resolve the blockage. Can your developers help out the others by doing code reviews? Are there small tasks for the blocking team that you can take over to get the blockage resolved more quickly?
Sometimes an unavoidable delay is a great time to institute new process changes that you want to do, but haven't had time for due to deadline pressures. So re-organize your source control if you need to or set it up if you don't have it, start writing tests to get started on TDD, set up a knowledgebase wiki and start writing articles for it, etc. Assign each stalled developer a topic to research and provide a training session on. Create some in-house tools you have been wanting or research the various bug trackers out there and test drive a few to decide which one to use. Install a new project management system. Refactor existing code. Etc.
Are there tasks you are supposed to do for the project, but nobody really likes doing such as updating documentation? This is a good time for this.
Finally, why are these circumstances happening? Did you do a poor job coordination with others? Start working right now on improving that so that you have fewer of these down times in the future.