We've seen several different blogging clients already come out for the iPhone, so it's hard to determine which one is the best one to use. After reviewing iBlogger, there really isn't a choice anymore. iBlogger offers the most support and features out of any blogging app for the iPhone, making it a must have for anyone who has a blog.
iBlogger works with the most popular blog engines (WordPress, Blojsom, Drupal, ExpressionEngine, MovableType, and TypePad) and blog hosting services (Wordpress.com, LifeType, LivingDot, My.Opera.com, SquareSpace, TypePad, Xanga, and Blogspot/Blogger). If those options aren't enough for you, they make it very clear that any developer can provide them with the information they need to be added to the list.
The actual software runs very similar to Ecto, the popular Mac blogging software. You have the ability to have multiple accounts, post your pictures directly to any of the accounts (blogspot coming soon), and even set all of the additional information you would on a desktop based blogging client. The only downfall of iBlogger is that you can't seem to schedule post for a later date.
iBlogger does have a decent sized price tag on it, but the fact is they're constantly working on new updates. Plopping down that cash now for guaranteed updates and new editions makes it very much worth it. You get a lot more control with this app then any of the other multiplatform apps. If you're just using WordPress, you'll have to determine whether you want to do delayed posting or position your pictures a little better.