Quick alerter post, to be amended later: judgment in R (on the application of Daley-Murdock) v Secretary of State for the Home Department [2011] EWCA Civ 161  is now available on BAILII and it looks like Mirza will follow soon. They were heard as conjoined appeals. The outcome of Mirza looks to have been positive from para 6 of Daley-Murdock:

In the conjoined appeals we decided that in the case of those appellants who do have a right of appeal against a decision to refuse to vary their leave to remain a generalised practice or policy of separating that decision from a decision as to whether to remove them is contrary to the policy and objects of the legislation, and that while there may be cases in which segregation of the two decisions may be justified, no such justification had been shown in the five conjoined appeals. Does the fact that this Appellant was an overstayer lead to a different conclusion?

The appeal in Daley-Murdock is actually dismissed on the facts, but it looks like, finally, there may be at least a partial resolution to the limbo problem.