You can use now the row provider to select the infopath form (rememeber that the view need contains the ID field).
The problems rendering fields with special characters is now solved.
Also I added a cell consumer interface to get the ID from other webpart as csegRollUp 

In the properties you need add the XSL (see previous version) and the name of the form library.

If you can´t display the infopath form, check if  you can get the XML from the server using the form Url. Some users are using a WSS environment where they don´t use DNS to resolve the url where WSS is located, they are using an entry in the hosts file. In this case the server can´t resolve the Url where the form is located. To solve this issue you can add the host name in the hosts file of your server.

Finally I have a first version (0.99) of my InfoPath viewer, first I want give thanks to my friend Gustavo, for testing the preliminary version and to make as always good suggestions.

Installation

stsadm -o addwppack -filename csegInfopathWebPart.cab -globalinstall  (use -force if you have installed the preliminary version)

Use

a) Create a view in your Form Library webpart containing the identifier of the list (the ID field).

b) Create a new webpart page, and insert the FormLibrary webpart and csegInfoPath webpart.

c) In the FormLibrary webpart select the view that contains the ID field, you need this view to connect with csegRollUp.

d) In the FormLibrary webpart menu select, “Conections” -> “Send row to” -> “csegInfoPathViewer” when prompt for field use the ID field.

e) Now fill the csegInfoPathViewer properties, you need specify the form library list name in the “List Name” field and put the XSL in the field XSL. (You can extract it from the infopath solution file, rename it as a .cab file and extract the xsl, then copy the content into the xsl property)

f) Now select an item and you can view the form in the csegInfoPathViewer.

This is my first attempt to do an infopath viewer webpart, this is only a test version that run. To run this webpart you need fill the properties, list (form library) field name of the field that you want show in the combo box to select the form and the xsl to render it. (You can extract it from the infopath solution file, rename it as a .cab file and extract the xsl, then copy the content into the xsl property)

  csegInfopathViewer.zip (6,82 KB)