[Update: No longer a rumor, this news has been confirmed by Microsoft's Major Nelson.]
According to everybody's favorite anonymous sources, Microsoft is about to update its policies regarding Xbox Live Arcade achievements.
Currently, achievements are set to a maximum of 20 for a combined 200 Gamerscore points, with an additional 50 points allowed in downloadable content. The new terms would raise these limits to 400 points spread across 30 achievements, with up to eight DLC achievements adding another 100 points.
The policy shift is said to be coming on June 1, although XBLA titles will have the option to exploit the new achievement cap from April.
Although a rumor at this stage, it's fairly plausible. XBLA games have only gotten bigger over the years, and this cap raise would be a natural step. You may now proceed to the comments section to let us know how little you care about achievements. Feel free to use the term, "E-peen" if you wish.
XBLA Achievement Policy Change Coming Soon [Xbox360Achievements]