Analysis from the BBC's Jim Muir:
If the Arab League observers had inhibited Syrian government forces from attacking residential areas, any such constraints now seem to be thrown to the winds.
Above is a map of Damascus. The triangle of blue dots highlights the Ummayad Square where Assad did his speech a few weeks ago, Kafr Souseh, where many intelligence buildings are, and Mezzeh, the main highway and thoroughfare for Damascus. In red are the areas where the BBC is reporting clashes between the Free Syrian Army and the Syrian regimes army. That is very close indeed.
At this stage, it's not clear how determined the Free Syrian Army will try to hold the positions in Damascus, or whether this was just a move to unnerve the regime and show that they can reach into the capital. The next forty eight hours should make things clearer.