itaysk

UPDATE: Since this post was published, lots of updates and fixes was released that effected implicit wildcard search for properties - The "Contains" operator was removed from advanced search UI. You CAN revert this. About keyword search - seems to default to "Equal" instead of  "Contains", expet for searching by "Author" or user profiles properties. More info here: http://blogs.microsoft.co.il/blogs/itaysk/archive/2009/04/16/contains-operator-disappeared-from-advanced-search.aspx

Here are tow facts I have discovered about property search in MOSS.
Just to be clear, when I say property search, I mean searching by any one of the managed properties defined, using keyword query, or advanced search.
Property search example using keyword search -
 
Property search example using advanced search -
 

Once we got that settled, lets talk about what happen when you search by properties.

Properties automatically support wildcard search

Yes that wildcard issue again. We all know wildcard search is supported in MOSS, but requires developing a custom search solution.
Having said that, if you search by properties and not by keywords, wildcard search is working implicitly. Even without including a wildcard character. (When using advanced search, the "Contains" operator makes it more clear)

Take this for instance:
I search for the following keyword: "Car" -  I might get results like "Car for sale.docx".
I search for the following property query: "Title: Car". I might get results like "Carnival.pdf".

See the difference? This can be particularly useful when you search for people by name, and you don't know exactly how they are spelled. So in order to find an employee called "Itay Shakury", you can just search for "It".

Properties doesn't obey thesaurus

Another tidbit about property searches. They doesn't seem to obey thesaurus. (more about setting up thesaurus here).

Take this for instance:
You define an expansion set in you thesaurus file as follows:

<expansion>
    _run
    _jog
</expansion>

Now you might expect that if you search for "run" , you will get results for "jog".
I search for the following keyword: "run" - I might get results like "I can run.docx" as well as results like "I can jog.docx".
I search for the following property query: "Title: Run" - I will get results like "I can run.docx", and WON'T get results like  "I can jog.docx".