Is it possible to send the current user's username as a parameter for my External Content Type query? I am on SharePoint 2010 Standard.
It is possible to create a filter based on the current user. If you're defining a ReadItem method, then you can even do this with the wizard in SharePoint Designer. It's a little more tricky if you want to do the same thing with a ReadList method.
This blog post goes into great detail about the process of adding a UserContext filter to a ReadList method. Here are the steps from a high level:
Here is some sample xml that gives a general idea of what this will look like in the XML:
Disclosure: I came across this solution while looking at this discussion thread.