Here my own analysis of this issue. I didn't try the FontForge workaround yet.

DejaVu versions tested:
2.23
2.30

DejaVu versions affected:
2.23
2.30

** Descripton of the issue **

** In Adobe Photoshop CS2 **
Photoshop version: CS2 (9.0, application language: French)
OS: OSX 10.4.9 PPC, system language: English

DejaVu Serif has 8 different weights. However, Adobe Photoshop CS2 displays only 7 of them. "DejaVu Serif Condensed Italic" is missing in the Font Type submenu. 

In addition to that, if the "DejaVu Serif Condensed" font style is selected, what is actually applied is "DejaVu Serif Condensed Italic". 

Therefore, we can apply the style "DejaVu Serif Condensed Italic", but there is no way to select the style "DejaVu Serif Condensed" (non-italic).

** In Adobe InDesign CS3 **
InDesign version: CS3 (5.0, application language: English)
OS: OSX 10.4.9 PPC, system language: English

The behaviour is entirely similar to Photoshop CS2: the item "DejaVu Serif > Condensed Italic" is missing from the menu. Upon selecting "DejaVu Serif > Condensed", what is actually displayed is the "Condensed Italic" style.

** In Apple FontBook **
FontBook version: 2.0.3 (69.3)
OS: OSX 10.4.9 PPC, system language: English

DejaVuSerifCondensed-Italic shows an unexpected behavior in Apple's FontBook: FontBook lists all the 8 styles, however two of them are named "Condensed", while "Condensed Italic" does not appear in the list. 

When selecting those two "Condensed" entries, the preview window shows that one of them (the first in the list) is actually the "Condensed Italic" style. When looking at the "Font Info" panel, we see the following:

* PostScript name: DejaVuSerifCondensed-Italic
* Full name: DejaVu Serif Italic Condensed
* Family: DejaVu Serif
* Style: Condensed

The last entry, "Style: Condensed", is obviously wrong, it should read "Style: Condensed Italic".

All other DejaVu fonts are displayed as expected in FontBook.

** In Apple TextEdit **
TextEdit version: 1.4 (220) on OSX 10.4.9 PPC
OS: OSX 10.4.9 PPC, system language: English

The "DejaVu Serif Condensed Italic" style actually exists, but it is wrongly listed as "DejaVu Serif Condensed > Book". In the font selection menu, there are two "Book" entries. Selecting the first one results in "DejaVu Serif Condensed", the second in "DejaVu Serif Condensed Italic".

All other DejaVu types work as expected in TextEdit.

One additional observation:

I found one application that displays the whole "DejaVu Serif Condensed" styles correctly on Mac OSX, and it's QuarkXPress 8.

My assumption is that when generating the font menus, QuarkXPress is reading the "Full name" field of the font, while Adobe's products are reading the "Style" field (what Bernhard has called "Preferred Style").

*** Bug 22394 has been marked as a duplicate of this bug. ***

This bug has been fixed in SVN. It happened because the script that generates the condensed styles wasn't updated when we switched the name from Serif Oblique to Serif Italic. It'll be available in the next release (or in the snapshots at http://dejavu.sourceforge.net/snapshots/ if you want it now).

Thank you Ben for that information: I installed the newest version from http://dejavu.sourceforge.net/snapshots/ (dejavu-fonts-ttf-2.30-20091003-2368) and the Serif Condensed types are now fully available, both in Photoshop CS2 and InDesign CS3.

However, this version of the font is producing crashes in Photoshop CS2 and InDesign CS3 upon selecting the "DejaVu Sans Mono Oblique" type -- an issue that previously occured on my machine with DejaVu 2.23, but seemed to be resolved with the regular 2.30 build. I will look for the appropriate bug # to report that.