what does this mean what could we invent with this tech.
Everything you can imagine, theroetically. For the next years though, we don't even know if Drexler nanomachines will be in the realm of fantasy or reality (due to issues created by atomic forces) so, well, this is really vague. We could reach picotechnology by 2070 or never reach it at all.
Thermodynamics dictates that we can't create nanomachines.
Despite this, there are nanomachines all around us, though we tend to call them viruses, bacteria, and cells. Also, we've developed nanomotors and nanoengines of various efficiencies and nanostructures. To be perfectly honest, it's all really a matter of creating a shell and nanocomputers because we've already developed all the parts.