So how to do that? I'm not going to run Apache+mod_php on the thing. :-/
I've started with Apache2, FastCGI, PHP via FCGI, installed eaccelerator for 60% speed-up.
All of this works reasonably well, except for PHP scripts that want PATH_INFO (like http://.../blog.php/2005/12/03/some_random_gunk). mod_fcgi passes the whole thing's pseudo file system path in PATH_TRANSLATED. The PHP FCGI process checks that path, sees that it doesn't exist (blog.php is a file after all), and immediately returns an unhelpful error.
I've worked around that thing with an ugly hack, but I suspect that the real fix would be to add this same hack to PHP instead.
NB: Oh, and if somebody could tell me why my mysql server's kernel randomly ignores incoming TCP connections for a few seconds every minute (and yes, it's the kernel), I'd be grateful. I suspect that the solution is going to be "upgrade to something newer than 2.6.12-9-686-smp (Ubuntu Breezy's kernel)"... :-/
NB2: There's also a mod_fcgid for Apache2. Hint: It's crap -- if all FCGI processes happen to be busy, I want new requests to be delayed. I do not want them to be rejected with a terse, hard-coded error message.