Yes.
1) Most newer PLCs have some PID loops built in to the CPU, and not into an extra I/O or specialty card. A-B and AutomatinDirect.com and GE and most others now do it this way. Most limit you to one or four or some other specific number of PID loops.
2) PID is just a mathematical equation, widely published, and essentially using only four function math. If you understand the algorithm, you can "roll your own" PID and do the calculations in ladder or whatever.
3) Depending on your application you may not even need PID - there are lots of ways to control a process.