Learn English – Phrases to give home address

This sentence alludes to a common device for announcing a surprising event, “I’ll give you three guesses wh— ...”:

I'll give you three guesses who the new manager is.
  Who?
Carol!
  Holy cow! no kidding?

Three guesses which children’s author insisted on writing a book about seven naked women before they’d write any more kids’ titles

The three guesses device (which is in origin a storytelling device for building suspense^†) suggests that the event is so improbable that even with three successively more far-fetched tries you will not succeed in guessing the right answer.

By contrast, “I'll give you one guess” suggests that the answer is so obvious you only need one guess to get it right. A common variant is

I’ll give you three guesses, and the first two don’t count.

^† For instance:

... when the little man stepped in shortly afterward and asked: "Now, my lady Queen, what's my name?" she asked first: "Is your name Conrad?"
   "No."
   "Is your name Harry?"
   "No."
   "Is your name perhaps, Rumpelstiltzkin?"
   "Some demon has told you that! some demon has told you that!" screamed the little man, and in his rage drove his right foot so far into the ground that it sank in up to his waist; then in a passion he seized the left foot with both hands and tore himself in two.

In addition to using Mark Hubbard’s “Thank you in advance for [keeping me informed]” (or just “Thanks in advance for [ … ]” in less formal situations) to express your thanks in advance without having to rely on context, you could also consider using a near-synonym for being thankful to use with the conditional would, for example:

“I would (I’d)[ greatly/very much] appreciate your keeping me informed.”

or (to emphasize the conditional notion even further):

“I’d be [extremely/very] grateful if you would (you’d)/could keep me informed.”

(Please note that, although it’s probably overstating the actual level of appreciation/gratitude, I think I would include greatly and extremely, especially in the above, “in advance” cases, but probably less so in the “after the fact” cases mentioned below. However, be careful not to “over-do” it because you could come across as being sarcastic or “sycophantic” [the English sense!], so on second thought, maybe the more restrained very/very much would be better in these cases where intensifying the gratitude might be in order because you are actually requesting a future favor at the same time.)

Regarding “after the fact” expressions of thankfulness (such as the one you made on “Overflow” and are asking about here), in addition to Mark’s use of the past tense (provided) or relying solely on context (which I agree can be ambiguous, especially in your example where it could easily be interpreted as an on-going request), you could consider changing “keeping” to “having kept” and “keep” to “kept” to use either with the same near-synonyms above (but in the unconditional present) or else (preferably, I think) simply with the original “Thank you/Thanks” construction, for example:

“I [do] [greatly/very much] appreciate your having kept me informed.”
(where the do would be an optional way to emphasize the appreciation)

“I am (I’m) [extremely/very] grateful that you kept me informed.”

Thank you (Thanks) for having kept me informed.

(But please see this relevant Word Reference thread that seems to confirm that we are, in fact, often (but not always?) at the mercy of sometimes ambiguous context in English (as indicated in user3169's answer). At least “Kelly B” begins his/her answer with “Yes, that's right,” so making the effort in our own speech to avoid the ambiguity would be not only admirable, but also grammatically and logically correct, although we'd still have to rely on context to interpret the meaning when spoken to us by somebody who is less concerned with clarity.)