I just received an email from ElephantDrive informing me that my legacy unlimited storage account will be terminated in 30 days, and that I must select a new plan.

In July 2009 ElephantDrive announced that they are no longer offering their $100 per year unlimited storage plan. ElephantDrive is now offering a $200 per year for 500GB plan.
In February 2011 Mozy announced that they are no longer offering their $55 per year unlimited storage plan. Mozy is now offering a $120 per year for 125GB plan.
In February 2011 Trend Micro SafeSync announced that they are bandwidth throttling large accounts. In March 2011 they announced that they are no longer offering their $35 per year unlimited storage plan. SafeSync is now offering a $150 per year for 150GB plan.
Carbonite offers a $55 per year for unlimited storage plan, but they are bandwidth throttling accounts over 35GB to 512Kbps and accounts over 200GB to 100Kbps access speeds.
AVG LiveKive offers an $80 per year for unlimited storage plan, but the terms of service defines unlimited as 500GB.
BackBlaze offers a $60 per year for unlimited storage plan.
CrashPlan offers a $50 per year for unlimited storage plan.
Neither BackBlazenor CrashPlan supports their unlimited plan on server class machines.

I currently have 2.1TB of data backed up online with ElephantDrive running on my Windows Server 2008 R2 machine. Needless to say, none of their new plans are affordable for that amount of storage. I either need to significantly trim down what I back up, or I need to find a new unlimited storage provider, that also allows installs on Windows Server.
For now, I’m uninstalling ElephantDrive.

[Update]
CrashPlan’s new v3 software installs and runs fine on Windows Server 2008 R2, and I have switched to using CrashPlan for my backup needs.

Here is an example snippet of the status emails I receive from CrashPlan:
Source -> TargetSelectedFilesBacked
Up %Last
ConnectedLast
BackupVM-STORAGE -> CrashPlan Central2.1TB ↑1KB423k 0100.0%2.5 hrs4.3 hrs