Something to think about: we all live in a big black hole.
Thoughts about SETI and SETI@home
It would be an odd Universe if we were the only intelligent life - but then it IS an odd Universe, so...
If there's other intelligent life out there, then I think we'd best be aware of it - though whether it's possible to be prepared for it is another question entirely.
Should we let 'them' know we're here? How paranoid are you? I think they'll notice us anyway - if they're looking. And looking in the right direction.
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.