I'm the PP above. I should add, I had a similar situation (albeit a decade ago) where I felt sort of strung along (3 interviews, all with them saying how perfect I was for the job, lots of delays). Finally, the offered me a job. I took it, and it turned out to be a horrible job. I realized why it took them so long to do anything... because there was a lot of internal problems, communication issues, tensions, competing visions for the department.
I left that job 9 months later.
Remember, the interview process isn't just for the company/organization to figure out if you are right for the job; it's also an opportunity for you to sort out if it is the kind of place you want to work. So pay close attention to red flags (i.e. being strung along, mislead, told they'd get back in a week and then hearing nothing). Because that is a synopsis of what it will be like working there and trying to move up the ladder.
If the problem is that it is vacation season, then a good employer would communicate that to applicants. They should know if August is a difficult month to get things processed and communicate that hiring decisions will be held until September because of it.
It just looks to me like either they are disorganized or slightly dishonest (i.e. they have a candidate in mind and are waiting to see if that candidate will accept). Either way, if you already have a solid job, I wouldn't jump ship for this one.
If you are in need of a job, that is a different story.