Its common sightseeing for me to see wordpress permalink untouch or  customized.

In my opinion permalink provided by wordpress really help in the eye of search engine.

For demonstration purpose I take a few blog from Wongkito Community :

>> Default

1st example : Take IT Or Leave IT

When I click the title, I’ll see this url :

http://blog.jafisnet.com/?p=200

As you see posting url use number . (/?p=200)

>> Custom

2nd example : Amarok aja deh

When I click on the title I saw this url  :

http://blog.ibunk.or.id/index.php/2008/06/26/amarok-aja-deh.ibunk

Posting url have components : index.php, year, month, posting title and .ibunk

Those url use wordpress permanent link feature which is accessible from here :

1. Click ‘Settings’ link.

2. Click Permalinks

3.  Common settings will list a few options

Just click on  ‘radio button’  to activate your option.

To produce url in the format that I use in my family blog :

http://keluarga.rasyid.net/2008/06/25/dari-simpati-ke-kartu-halo.html

what I have to type in  ‘Custom Structure’ field is :

/%year%/%monthnum%/%day%/%postname%.html

Click button  “Save Changes’ to apply.

P.S :

Permalink will make your transition from blogspot to wordpress conversion easier and make sure your existing post in search engine left as is

More reading for complete reference in wordpress permalink click here.