We've just launched an all-new line of dedicated servers. Most of the information you'll want to know is available on our web site, but here's the TL;DR:
More processing power: Xeon E5-2670 v3 with 12 cores (24 threads). Our previous dedicated servers all had 4 to 6 cores, so this is a pretty huge upgrade.
More memory: 16, 32, or 64 GB of RAM. (Existing options for 4, 8, or 16 GB are still available as well, but the new hardware I'm describing here are only available with the newer, bigger servers.)
More storage options: 2 TB hard disk or 240 GB SSD. Both configurations have two drives in RAID 1.
These new servers are all available immediately through the DreamHost Panel for existing customers (click "Add a Dedicated Server" in the Dedicated Server Dashboard), or at signup.dreamhost.com if you don't already have an account.