I was lucky enough to have a couple of days free in Beojing last week. One day I went to the old summer palace that I had found to be very good for birding previously. Unfortunately, Beijing seems to be cleaning up the area (due to olympics?), so what were previously reed beds and muddy scrapes, are now completely drained, with the reed beds ploughed, and I expect that eventually they will be 'perfect' lakes with no birds. Only birds of interest were Garganey d & Dark-throated Thrush.
I've not been impressed with the new summer palace in the past due to the number of people, so avoided it this visit.
Best place I visited was the Fragrent Hills (100RMB (10 Euro) each way taxi from central Beijing). Avoid weekends as all you'll see is people, and all you'll hear is Chinese folk music. As it was, on a Monday, highlights I managed to see were Daurian Redstart, red-flanked robin and plain laughing thrush. It's not like an English reserve, but this is China - it's the best you'll get: get there early, and ignore/avoid the people and the noise.
Julian