This is all through rebel sources, so take it with a grain of salt, but videos uploaded to YouTube appear to support their claims of having seized a military base just south of Damascus. If true, and if they hold it, this would mark a significant advance for the rebels, one that brings them a step closer to the capital city. Al Jazeera English's compilation goes through what the videos appear to show. Here's a snippet from a Reuters' report on the rebels' claimed advance:

The base is on the edge of Hajar al-Aswad district, normally home to thousands of poor refugees from the Israeli-occupied Golan Heights who were at the forefront of the movement against Assad's autocratic rule at the beginning of the revolt.

After months of slow progress, marked by poor organisation and supply, rebels have taken over several army positions in outlying regions in the last week, including a Special Forces base near the northern city of Aleppo and a small military airport in the east, on the border with Iraq.