Note: this doesn't work across ABI changes, i.e. when 3.2.0-4-amd64 becomes 3.2.0-5-amd64
Find the package version for the most recently installed kernel:
dpkg -l linux-image-$(uname -r) | awk '/^ii/{ print $3 }'
Get the same information from the running kernel:
uname --kernel-version | awk '{ print $NF }'
Compare.