Yes, but cleaner syntax for it would be nice. Right now it looks quite messy:

  private Lazy<string> _someVariable =new Lazy<string>(SomeClass.IOnlyWantToCallYouOnce);
  public string SomeVariable {
    get { return _someVariable.Value; }
  }

Imagine the same things with a long lambda inside.

... and writing your own Lazy<T> with time- or otherwise-limited cache validity is not a problem, also.