Yes you can, but you need to keep both the scope and the context mind.
Regarding scope: high-speed rail is mostly interesting for journeys in the 50-400 mile range; for shorter journeys, the many stops would bring down the average speed too much, and for longer journeys a single-hop plane transfer is faster.
I regularly travel the high-speed net in Europe, and I love it: No of that checking-in business; I get to the station 10 minutes before the train leaves, sit down on my reserved seat, and soon I am speeding through Southern Germany at 200 mph. Still, a ~400 mile journey (case in point: Zurich-Aachen) takes me 6 hours downtown to downtown. The main reasons for that slow ~70 mph average are slow links in Switzerland, and the relatively high number of stops in densely populated Germany. Still, this is 70 mph average, at (when planned somewhat in advance) EUR 120 for a return ticket.
Now, in the US, the SF-LA corridor and the East-cost are excellent choices for such a network. Especially the SF-LA link could do with only a few stops (LA, Bakersfield, Fresno, (Stockton), San Jose, SF, say), so one could push for >80 mph average. This would bring down travel time from _downtown_ LA to _downtown_ SF to 5 hours. Such a journey would be the efficiency limit for a fast train though, since there is a good flight here. Perhaps LA-Bakersfield (~120 miles) in an hour would be a better example.
The thing to remember though, and that bring me to the "context" part of the title, is that high-speed rail cannot exist on its own. Although the connections for larger distances already exist (planes), one definitely needs connections to shorter-distance transport modalities. Examples are fast commuter train for a metropolitan area (relatively high number of stops, but fast acceleration and deceleration), tram/bus networks in the city (and _adaptations_ to the city for that, so that trams and busses are never in traffic jams, etc.). Not having this latter modality leaves you with a "last mile" problem. If you cannot get to the station fast, often, and safe, you won't use your high-speed train, and you could hardly be blamed for that.
