For all those Ubuntu users with the following error:

Starting JUploadr…
Java exec found in PATH. Verifying…
Suitable java version found [java = 1.4.2]
Configuring environment…
GCJ is an incompatible version of java

Do the following:

sudo update-alternatives –config java

You will see a list of java executables. Just choose Sun’s version.
if you need help setting up installing Java in Ubuntu, follow this [...]