I came upon a thread post elsewhere that made me want to pose this question:

Anyone used AutoIt with Selenium Grid? To address issues like file upload/download, and authentication login dialog windows, etc.

AutoIt is a known good solution to workaround those issues where Selenium 1/RC is lacking, but it may be trickier to implement in grid environment, particularly as the Selenium test itself never specifically references the remote host to connect to (handled by the grid) but for the AutoIt portion, there is no "grid" controller to route the automation calls, so you may have to specifically reference the remote host to connect to (via custom implementation or PSExec.exe or winexe for Linux, etc.).