You know, flipping through the printed product there really is a LOT of information from old issues of the magazine. The feats, prestige classes, and magic items are mostly recent, but the monsters, "classics," classes, and races all come from a variety of sources. Specifically, the Compendium contains material from the following issues, all of which predate third edition:
Strategic Review
-------------------
1
Dragon
--------
17
38
39
48
50
59
60
65
69
76
78
89
93
135
140
159
162
175
180
184
199
210
223
238
248
267
271
Based on the above listing, I think it's fair to say that comments about the Compendium not including enough "old stuff" should be taken with a grain of salt. There are sections comprised mostly of newer material, but for feats and prestige classes, it's because those things did not exist prior to third edition. There are more than 4000 pages of material in the Dragon archive. There's no way we could have fit all of it in one book, but even with the new material, the Dragon Compendium Volume 1 contains a good sample of excellent material from all eras of the magazine's rich history.
Is there more good stuff to be culled? Of course, and we hope to be able to bring that to you over the course of the next few years.
--Erik Mona
Editor-in-Chief
Dragon & Dungeon