Its certainly important to keep a close eye on the Immigration Rules. UKBA could perhaps be accused of being sore losers at times. CDS (PBS: “available”: Article Eight) Brazil  UKUT 00305 (IAC) is an important tribunal case that held (amongst other things) that a Tier 4 Student applicant could rely on funds from willing 3rd parties.
The critical issue was that whilst UKBA may have liked to be more restrictive, the rules were not drafted as such, merely stating that an applicant had to have funds 'available'.
UKBA's response to losing? Change the rules! In March 2011, Statement of Changes HC908 changed the rules to be more restrictive.
This trend is fairly common. Rules are drafted, challenges or attempts to clarify are brought to the tribunal, a case comes out and then the rules are changed. The PBS system rules in particular have become an utterly confusing mess.
This incremental alteration is probably not in anyone's interest. Each change brings its own problems of interpretation, and what you are left with is an ever shifting position, with important and well reasoned cases almost out of date by the time they are promulgated.