How can I list all system restore points?

Run PowerShell as an administrator. At the prompt:

Get-ComputerRestorePoint

This will list all the system restore points.

PowerShell offers four Cmdlets to manage system restore and/or restore points:

1. Disable-ComputerRestore

2. Enable-ComputerRestore

3. Get-ComputerRestorePoint

4. Restore-Computer

For assistance with any of them, you can add get-help in front of the Cmdlet, i.e.

get-help Get-ComputerRestorePoint

System Restore is implemented using the Volume Shadow Copy Service (Volume Snapshot Service, VSS). As such, you can use vssadmin in an elevated command prompt to list all of the restore points:

vssadmin List Shadows

Note that Windows Backup also uses VSS, with shadow copies stored on both the system and backup drives, so if your backup drive is connected, the shadow copies stored on the backup drive corresponding to these backups will be listed as well. Add /for=C: to specify the volume you want to list the shadow copies for, replacing C: with the volume letter of your choice if it is not C:.

While this isn't the easiest way to work with restore points, you can use the creation date and time and shadow copy ID listed in the output from the above command to delete specific restore points, using the vssadmin Delete Shadows command. You can also create restore points with vssadmin Create Shadow and change the amount of space available to restore points with vssadmin Resize ShadowStorage. More information about vssadmin is available in this TechNet article.

While I'm late to this question, this is possibly of use to someone. If you want to know how long ago the last restore point was, the restore point creation date property needs to be converted before use.

 (Get-ComputerRestorePoint  | select  -first 1 @{label="Date"; Expression={$_.ConvertToDateTime($_.CreationTime)}}).Date

and to get how long ago it was you need a timespan calculation:

new-timespan -start ((Get-ComputerRestorePoint  | sort CreationTime -descending | select  -first 1 @{label="Date"; Expression={$_.ConvertToDateTime($_.CreationTime)}}).Date) -end (get-date)

hopefully this will save someone a bit a frustration.