I went to the new 'Unveiled' thing at the Saatchi Gallery last week. Really, really good. Especially loved the 'Ghost' figures by Kader Attia. Absolutely amazing, the photos don't really do it justice.
Also saw the Saul Steinberg exhibition at Dulwich Picture Gallery. We went on the last day so it was a bit rushed, but it was great.
I'm sure there's been some more, but I can't remember.
Next up on the list of things to go to:
Le Corbusier thing at the Barbican
Gerhard Richter portraits at the NPG
Paintings from the 80s at the Tate Modern, and the Rodchenko and Popova thing.
Anything else on that's good? I need to make more use of all this free time I have.