In late June TfL published a factsheet on road casualties in 2011, which you can find alongside previous versions here. There were 29,257 casualties recorded by the police in 2011 (inevitably an under-estimate, since many injuries don’t get reported, particularly the less serious ones). Of these, 159 were fatalities, 2,646 were serious injuries, and 26,452 were slight injuries.
The number of people killed or seriously injured (KSI) fell 3% from 2010 to the lowest number since 1986 (the earliest year of police reporting at Greater London level). But there were huge differences in trend for different categories of road user: while the number of car occupant KSIs fell by 31% and the number of bus or coach occupants by 12%, the number of cycling KSIs increased by 22% and the number of pedestrian KSIs by 7%.
Of course, these divergent trends are partly due to different trends in traffic for each mode, with car traffic generally falling and cycling rising in recent years. But it’s very unlikely that car traffic fell by 31% or that cycling rose by 22%, so it is highly probable that the car casualty rate fell and the cycle casualty rate rose. We should get more evidence on casualty rates when DfT update this table and others in a month or so.
It is also worth noting that DfT publish very detailed data for every single recorded casualty recorded on data.gov.uk. The data is at case level so you can analyse it any way you like, but be warned that the data is quite complex (you may need to match vehicle records with casualty records, for example) so it might take some time to understand.