The only way I'd know of would be a background process. You could either start this automatically with .bash_profile or similar (but you would probably want to check you were in an xterm and also this will cause load as every window will display it), or start it once manually when you login.
So for example using your code above, create a file in the PATH called printload set to exec containing:
#!/bin/bash function curr_load { # interval wrapper here, or somewhere at any rate ;-) uptime } while true; do echo -ne "\033]0;$@$ [`curr_load`]\007" sleep 3 done
And then just start printload with:
printload &
Which you can of course put itself into a script to be called automatically or manually.
** NOTE: Not tested for syntax but should work in theory **