Is it possible to capture a Ctrl+C signal and run a cleanup function, in a "defer" fashion?

You can use the os/signal package to handle incoming signals. Ctrl+C is SIGINT, so you can use this to trap os.Interrupt.

c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
go func(){
    for sig := range c {
        // sig is a ^C, handle it
    }
}()

The manner in which you cause your program to terminate and print information is entirely up to you.

This works:

package main

import (
    "fmt"
    "os"
    "os/signal"
    "syscall"
    "time" // or "runtime"
)

func cleanup() {
    fmt.Println("cleanup")
}

func main() {
    c := make(chan os.Signal)
    signal.Notify(c, os.Interrupt, syscall.SIGTERM)
    go func() {
        <-c
        cleanup()
        os.Exit(1)
    }()

    for {
        fmt.Println("sleeping...")
        time.Sleep(10 * time.Second) // or runtime.Gosched() or similar per @misterbee
    }
}

To add slightly to the other answers, if you actually want to catch SIGTERM (the default signal sent by the kill command), you can use syscall.SIGTERM in place of os.Interrupt. Beware that the syscall interface is system-specific and might not work everywhere (e.g. on windows). But it works nicely to catch both:

c := make(chan os.Signal, 2)
signal.Notify(c, os.Interrupt, syscall.SIGTERM)
....