If you are using the graphical version of 0.9.0 on any platform, you must update immediately.
If you are using packages from your Linux distro (Ubuntu PPA included), 0.9.1 has no changes for you.
Instead, you must upgrade to a fixed OpenSSL version.
So if libssl1.0.0 has been updated then all is good and we can still use 0.9.0 ?