Pedantic

"IT infrastructure" is about stuff like system administration, network engineering and security management. Infrastructure people deal with server farms, firewalls, routers/switches/cables and basic network services like DNS, NTP, etc.

When a programmer type says, "I implemented X," he means he wrote the software for X. Here X may mean "a servlet + JSP combo report generation web app" or "that quick-and-dirty load balancing DNS server" or "freely available kernel of a UNIX-like OS; comes with source code."

When an infrastructure type says, "I implemented X," where X may be "load-balanced firewall cluster" or "4-tier 'reverse proxy + web server + messaging middleware + database' enterprise application architecture," or "multicast video feed for human supervision of robotic tentacles," he usually means he put the hardware/software/networking pieces for X together and made the whole thing work.

"Deploy" is a better word than "implement" in the latter context; it is not as popular, though.