0.8.1 is not an update on the previous 0.8.0 version. 0.8.1 is the entire program and that is why it's 300MB.
There will be no 0.8.1 patch to just upgrade 0.8.0 due to the major changes between both packages.
I'm not aware of any 0.8.1 Debian packages as of yet, though Google may bring something up.