mod_rails is a new alternative to mongrel, thin, etc that claims to be
faster, more robust and easier to set up. Ryan Bates from Railscasts has a
video on the setup
It is an apache module so if you are using ngnix or lightspeed, you would need to switch.
For me, I was already using Apache as a proxy to pack of mongrels. The switch was very easy and it seems to be working well. One thing I haven't worked out yet is where my production logs are being written. Ostensibly, apache should be writing them but I am trying to figure out where.
mod_rails seems to be very well done and thoroughly tested plus it has support from a lot of important members of the community. Given
Zed's departure and various challenges/issues many have had with mongrel, this might be a good alternative going forward.