What do you think?

I had an interview today, it lasted about 10 minutes. It was for a job I think I could do well and maybe even enjoy it, but it only lasted about 10 minutes. I sent a "thank you" email when I got home. My question is if the interview was only about 10 minutes long is that a good or bad sign? I've had interviews that lasted longer and I really thought I had the job but I was wrong. So I need your opinions please. Thanks.

More important what was said in that 10 minutes than the actual length itself. How complex is the job? Do you have related experience? What was the last thing the interviewer said to you? (something like "We are interviewing this week and will let you know by Friday if wed like you to come in for a second interview/if you got the job)

The last thing they said was thanks for coming in.

It depends, we are interviewing soon and because of our own schedules, we have to limit the time spent on each interview, 15 mins, knowing that my boss can't stick to a schedule and will go 20, but after that, I will have someone come in and interrupt, usually, our interviews are 30-40 mins

I would've thought a lot longer would be normal, but they may have had a lot to get through.

I've never had one that only lasted 10 minutes. Where I work, usually they initially take a person to lunch, then if they like them, bring them in for a pretty much full day interview. I guess every company is different.

The other time I have seen them do short interviews like that is when they already have someone they want to hire but have to be seen to have a hiring process so go through the motions

Again, all this depends on the specific job. I would wager most entry level customer service positions (for example), a 30 minute interview would be overkill. A CEO candidate, I would expect to have a couple days of presentations and meetings as part of the interview.
Ive also personally conducted screening interviews myself, that were never more than 20 minutes long, which was more than long enough to forward the candidate on to the more important person who is doing decisive interviews.

Follow up on the interview early next week. Say you were pleased to have the opportunity to come in and are inquiring as to when they will know about who they are hiring

I've been through 10 minute interviews - one I got the job, the others I didn't. So it depends on a lot of factors, I think.

It really does depend on the person doing the interview. Its almost impossible to say how it went without us being there. Im looking for a job too BTW