I am able to build this without problem on Ubuntu Edgy.
Since liblzo2 isn't normally installed, I'm hesitant to include this in libhadoop.so, since I think libhadoop.so would then no longer link unless folks have liblzo2 installed. (This is different from zlib, which is normally installed on most systems.) It's a pain to build a separate library, but I don't see an alternative.
Also, can you please add a unit test? This should be a no-op when the native code isn't available. This could be a simple addition to TestSequenceFile#testSequenceFile, having it test another codec.