It didn't stop del.icio.us. If you build it, they will come.
It may have helped them in the beginning but it seems that there must have been some detrimental side effects in the long term or I'm sure they would not have switched.
myapp.me.uk does not, quite, have the same draw.
To the OP I'd say if you already run it from a .com domain adding .me.uk cant hurt!
If the .me adds to the name (say, for example, find.me.uk) then 100% go for it :D
Trust is a funny thing: if your userbase is hardened hackers like the HN lot then you might end up (at least initially) with a trust issue - but the general public aren't going to care that much.
Though you do raise a good point about people being confused: but if you own .com and .co.uk variants then I doubt it will account for much loss of traffic :D
I think the opposite is true - "hardened hackers" may judge the TLD less than the general public.
Eg, I run a couple of small websites, and I know that .com is a matter of routing, and says little about the intention of my website. However, a casual user might see .com as more of a directory than a routing issue.
A few years ago I had a couple of people try and convince me that .org was reserved for non-profit organisations. While that might be the intended usage, it certainly isn't mandatory.
SCHEDULE F
ELIGIBILITY AND ALLOCATION RULES FOR ORG.AU
The org.au 2LD is for non-commercial organisations.
The following rules are to be read in conjunction with the Eligibility and Allocation Rules for All Open 2LDs, contained in Schedule A of this document.
1. To be eligible in the org.au 2LD, registrants must be: a) an association incorporated in any Australian State or Territory; or b) a political party registered with the Australian Electoral Commission; or c) a trade union or other organisation registered under the Workplace Relations Act 1996; or d) a sporting or special interest club operating in Australia; or e) a charity operating in Australia, as defined in the registrant’s constitution or other documents of incorporation; or f) a non-profit organisation operating in Australia, as defined in the registrant’s constitution or other documents of incorporation.
2. Domain names in the org.au 2LD must be: a) an exact match, abbreviation or acronym of the registrant’s name; or b) otherwise closely and substantially connected to the registrant.
I'm UK based - I'm more likely to remember .me or .co.uk than I am .me.uk
So by no difference I meant there is no real difference to the UK public between the 2 (but me.uk is probably a safer bet).
(btw the site in question normalizes to .com so there is no infered bia by the "browse" url).