Question: What is the latest version of iText? And what is the maven dependency for that?

Answer: 
You need to pay attention to the license for the Java version of iText:

* iText `2.1.7`: the latest **official** release by iText Group NV, under the `MPL` & `GPL` license, with `com.lowagie` groupId;
* iText `4.2.1`: the latest **unofficial** release by ymasory/InProTopia, under the `MPL` & `GPL` license, with `com.lowagie` groupId;
* iText `5.0.0` and higher: released by iText Group NV, under the `AGPL` license, with `com.itextpdf` groupId. One monolithic jar.
* iText `7.0.0` and higher: released by iText Group NV, under the `AGPL` license, with `com.itextpdf` groupId. Several modular jars.

Here you can find 2.1.7 and 4.2.x versions on Maven Repository:

Find before 5.x versions:
<http://search.maven.org/#search|gav|1|g%3A%22com.lowagie%22%20AND%20a%3A%22itext%22>

Find 5.x versions:
<http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22com.itextpdf%22%20AND%20a%3A%22itextpdf%22>

You may want to stick with the MPL & GPL versions, unless you are available to follow the AGPL license specification... 

EDIT: 
You should pay attention on which version you are choosing;

According to Bruno Lowagie comment, [versions 2.1.x are deprecated](http://lowagie.com/itext2) and should not be used due to technical and legal reasons.
```
This was the latest release as of today

<!-- http://mvnrepository.com/artifact/com.itextpdf/itextpdf -->

<dependency>
<groupId>com.itextpdf</groupId>
<artifactId>itextpdf</artifactId>
<version>5.5.9</version>
</dependency>

```