I just helped a friend today who has two customers still running sites on Joomla 1.0. He is upgrading his servers to run mysql5.x and the Joomla 1.0 installs were not displaying any content. This meant it was time to migrate (it was well past that time actually).
I had him send me an sql dump of the databases and then I imported (one at a time) each dump into a database called "client10". I then did two very quick, and basic installs of Joomla 1.5 and Joomla 1.7.0, each using databases named "client15" and "client17" respectively.
After logging in to the 1.5 site, I installed the free 1.0-1.5 migrator mtwMigrator (use version 0.2.1). This migrator grabbed from the database "client10" everything from the options I selected and placed all in the database "client15". After a quick check that articles and users listed in the 1.5 install I logged out.
Next, I logged into the 1.7 site and installed the commercial 1.5-1.7 migrator SP Upgrade. This component is absolutely worth it! It grabbed from the database "client15" all I asked it to grab and placed all in the database "client17".
The final step for helping my friend was to do an SQL dump of the database "client17" and send it to him to use as as a base for rebuilding the client's sites with Joomla 1.7 installs on his servers.
Migrating from Joomla 1.5 to 1.7 does not leave you with a pristine, shiny, ready to go site. But it does leave you at a point where your articles, users, and many other things are there ready for you to rebuild your site in Joomla 1.7 - which in my opinion is awesome.
If you have a Joomla site you are looking to migrate to from 1.0 or 1.5 to 1.7 and you are looking for someone to hire to do so, send me an e-mail and let's see what can be worked out for your unique content.